Vertex 70vs Manual

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User Manual

1007253

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All rights reserved. No part of this manual may be reproduced or transmitted in any form or by any means including printing, photocopying, microfilm, electronic systems etc. without our prior written per-mission. Brand names, registered trademarks etc. used in this manual, even if not explicitly marked as such, are not to be considered unprotected by trademarks law. They are the property of their respective owner.

The following publication has been worked out with utmost care. However, Bruker Optik GmbH does not accept any liability for the correctness of the information. Bruker Optik GmbH reserves the right to make changes to the products described in this manual without notice.

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T

ABLE

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C

ONTENTS

1 Safety . . . 1

General Information . . . 1

Warning Labels . . . 2

Safety Instructions . . . 4

2 General . . . 5

3 Installation . . . 7

General Information . . . 7

Delivery Scope . . . 7

Site Requirements . . . 9

Connecting VERTEX 70v to the Power Supply . . . 11

Connecting VERTEX 70v to a PC . . . 12

Connecting VERTEX 70v to the Vacuum Pump . . . 13

Connecting VERTEX 70v to the Purge Gas Line . . . 15

4 Overview . . . 19

General Information . . . 19

External Components. . . 20

Internal Components . . . 25

Optical Path . . . 29

5 Operation . . . 31

General Information . . . 31

Switching VERTEX 70v On and Off . . . 31

QuickLock. . . 33

Automatic Accessory Recognition . . . 35

Performing a Measurement . . . 35

Evacuating and Venting the Spectrometer. . . 36

Optimizing the Vacuum Operation of the Spectrometer. . . 40

Purging the Spectrometer . . . 43

Exchanging the Beamsplitter . . . 46

Exchanging the Detector . . . 50

Cooling an MCT Detector. . . 52

6 Maintenance and Repair . . . 57

General Information . . . 57

Evacuating the MCT Detector Dewar. . . 58

Replacing the Laser Module. . . 61

Replacing a defective IR Source . . . 66

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Replacing the Sample Compartment Windows . . . 69

Cleaning the Instrument . . . 73

Maintaining the Vacuum Pump . . . 73

7 Troubleshooting . . . 75

General Information . . . 75

Diagnostic Means. . . 76

Problem - Possible Cause - Solution . . . 85

A Specifications . . . 101

B Consumable Spares . . . 103

C Default Parameter . . . 105

D Dimensional Drawings . . . 109

E Connecting VERTEX 70v to PC . . . 115

General Information . . . 115

Possible Connection Topologies . . . 116

Selecting Network Addresses . . . 119

Assigning Network Addresses . . . 120

Checking the Connection . . . 123

F Electronics and Power Supply . . . 125

Electronics Panel . . . 125

Power Supply Panel . . . 128

G Firmware Update . . . 131

General Information . . . 131

Updating the Firmware . . . 132

Restoring a previous Firmware Version . . . 134

Backing up the current Firmware Version . . . 135

H Sample Preparation . . . 137

General Information . . . 137

Sample Preparation Techniques . . . 139

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S

A F E T Y

1

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G E N E R A L I N F O R M A T I O N

Read the following safety instructions carefully before putting the spectrometer into operation. Keep this manual in a suitable place for future reference.

Always observe the instructions described in this manual to ensure user safety and to avoid property damage. Improper use or failure to follow these safety instructions can result in serious injuries and/or property damage. Any non-observance of the precau-tions will infringe the intended use (i.e. performing spectroscopic measurements) of the spectrometer. In this case Bruker Optik GmbH will not assume any liability.

It is the operator’s duty to plan and implement all necessary safety measures and to supervise their observance. Moreover, the operator must ensure that the spectrometer is in proper functioning condition. A safe and faultless operation can only be guaranteed if the spectrometer is transported, stored, installed, operated and maintained properly according to the procedures described in this manual.

Never remove or deactivate any supporting safety systems during spectrometer opera-tion. Ensure that objects and/or material not required for the measurement is out of the spectrometer operating area.

The spectrometer complies with the IEC/EN 61010-1 safety regulations.

P r o t e c t i v e E a r t h i n g

To avoid personal injuries and/or property damage caused by electrical power, the spectrometer is equipped with a safety plug. Connect this plug only to a socket outlet with earthing contact. Make sure that the socket complies with IEC (International Elec-trotechnical Commission).

Q u a l i f i e d P e r s o n n e l

Primary installation and all maintenance and repair works not described in this manual should only be performed by Bruker service personnel. Only authorized operating per-sonnel that have been briefed about the spectrometer operation and all relevant safety aspects should operate and maintain (i.e. only maintenance works that are described in this manual) the spectrometer.

All repairs, adjustments and alignments on any spectrometer component must be per-formed in accordance with the safety regulations and standards applied in the country in which the instrument is installed.

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Warning Labels

C o r r e c t U s a g e

The spectrometer and its components should only be used according to the instructions described in the manual or advised by a Bruker engineer. In case of accessories or components made by other manufacturers and used in connection with the spectrome-ter, Bruker does not assume any liability for safe operation and proper functioning.

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W A R N I N G L A B E L S

When operating the spectrometer you have to observe a number of safety instructions which are highlighted by various warning labels. This section describes the warning labels and explains their meaning. All warning labels on the spectrometer must always be kept legible. Immediately replace a worn or damaged label.

The following warning labels indicate different dangerous situations which may be caused by improper use of the spectrometer.

C a u t i o n - G e n e r a l H a z a r d

This warning symbol indicates general hazard. Observe the safety instructions and follow the precautions described to avoid personal injury and/or property damage.

C a u t i o n - E l e c t r i c a l S h o c k

This warning symbol indicates electrical hazard. The symbol is located near live parts or on enclosures behind which are live parts that represent an accidental contact hazard. Never touch these parts. Before removing the corresponding compartment covers and beginning any maintenance or repair work, first turn off the mains switch and unplug the main power cable. Ensure that all live parts do not come into contact with a conductive sub-stance or liquid. Non-observance of these safety instructions can cause severe personal injury and/or property damage.

C a u t i o n - H o t S u r f a c e

This warning symbol indicates components and surfaces which can become very hot during spectrometer operation. Do not touch these com-ponents and surfaces. Risk of skin burn! Be careful when operating near hot components and/or surfaces.

C a u t i o n - L a s e r R a d i a t i o n

This warning symbol indicates the existence of laser radiation. Never look directly into the laser beam or use any kind of optical instruments to do so. Otherwise permanent eye damage can be the result.

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Warning Labels

Besides the dangers described above, there can also be hazardous situations caused by the sample material. Depending on the type of hazardous substances you work with, you have to observe specific substance-relevant safety instructions. Put on the corre-sponding warning label on the appropriate spectrometer position. The label must be legible and permanently discernible. The following list contains some examples of haz-ardous substances:

C a u t i o n - F r o s t b i t e

This warning symbol indicates cryogenic materials (e.g. liquid nitrogen) required to operate the spectrometer (e.g. cooling detector). Skin contact with these liquids or cooled components causes severe frostbite. Always handle the liquids with utmost care. Observe the safety instructions for handling of cryogenic liquids.

C a u t i o n - H a r m f u l M a t e r i a l

This warning symbol indicates the existence of harmful or irritant material (e.g. the window material BaF₂). Observe the safety instructions on the packaging, and the safety data sheets attached. Non-observance may cause personal injury.

C a u t i o n - T o x i c M a t e r i a l

This warning symbol indicates the existence of toxic material (e.g. the win-dow material KRS-5). Observe the safety instructions on the packaging, and the safety data sheets attached. Non-observance may cause severe personal injury or even death.

C a u t i o n - I n f e c t i o u s M a t e r i a l

This warning symbol indicates the possible presence of bio-hazardous and infectious material. When working with this kind of material always, observe the prevailing laboratory safety regulations and take all necessary precau-tions and disinfection measures (e.g. wearing protective clothing, masks, gloves etc.). Failure to do so may cause severe personal injury or even death. (For information on how to use, dilute and efficiently apply disinfec-tants, refer to the Laboratory Biosafety Manual: 1993 by WHO - World Health Organization.)

C a u t i o n - R a d i o a c t i v e M a t e r i a l

This warning symbol indicates the possible presence of radioactivity. When working with radioactive material, always observe the safety regulations and take all necessary protective measures (e.g. wearing protective cloth-ing, masks gloves etc.). Failure to do so may cause severe personal injury or even death.

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1

Safety Instructions

W a s t e D i s p o s a l

Dispose all waste produced (chemicals, infectious and radioactively contaminated sub-stances etc.) according to the prevailing laboratory regulations. Detergents and clean-ing agents must be disposed accordclean-ing to the local waste regulations.

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S A F E T Y I N S T R U C T I O N S

The following chapters describe all relevant safety aspects of the spectrometer opera-tion. Depending on the degree of hazard the safety instructions are classified as fol-lows:

Danger indicates that death, severe personal injury or substantial property damage WILL result if proper precautions are not taken.

Warning indicates that death, severe personal injury or substantial property damage CAN result if proper precautions are not taken.

Caution indicates that minor personal injury or property damage CAN result if proper precautions are not taken.

Note draws your attention to particularly important information on the product, e.g. product operation or to a special part of the manual.

The safety instructions Danger, Warning and Caution stand out by the corresponding warning labels.

C a u t i o n - C o r r o s i v e S u b s t a n c e

This warning symbol indicates the possible presence of corrosive sub-stances. When working with corrosive substances, always observe the lab-oratory safety regulations and take protective measures (e.g. wearing protective masks and gloves). Failure to do so may cause severe personal injury or even death.

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G

E N E R A L

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VERTEX 70v is an evacuable, fully digital FT-IR spectrometer for demanding R&D applications. The spectrometer is equipped with a number of features such as AAR (Automatic Accessory Recognition) ACR (Automatic Component Recognition) and Per-formanceGuard that facilitate performing spectroscopic measurements and ensure reli-able measurement results. The function AAR identifies automatically the accessory installed in the sample compartment, performs several tests and loads automatically the corresponding experiment file including the pre-defined measurement parameters. The feature ACR recognizes automatically the currently installed optical components like source, detector and beamsplitter. These components are electronically coded so that the spectrometer firmware can recognize them. This information is passed on to the application software OPUS. The purpose of ACR is to enable the user to select the right optics parameters in OPUS. In addition, the spectrometer components are monitored permanently to ensure that they operate within the specification range. This feature is called Performance Guard. Its purpose is to facilitate fault diagnostics and maintenance. The data acquisition is based on a free running delta-sigma, dual-channel A/D converter with 24-bit dynamic range. The A/D converter is integrated into the detector preamplifier electronics. The DigiTect technology ensures a signal transmission free from interfer-ences and guarantees the highest signal-to-noise ratio.

VERTEX 70v can be controlled by any data system (PC workstation, notebook etc.) on which the operating system Microsoft Windows and the spectroscopic software OPUS is installed. The Ethernet connection provides the possibility to control the spectrometer also via your intranet or the internet.

The standard spectrometer configuration is designed for data acquisition in the mid IR region. Optionally, VERTEX 70v can be equipped with additional optical components to cover the whole spectral range - starting in the far infrared or THz region at 10cm-1 up to the ultraviolet region at 28,000cm-1. Due to the pre-aligned optical components and the permanently aligned RockSolid interferometer, the spectral range can be changed eas-ily. If you work with the advanced spectrometer configuration (i.e. two detector positions and two source positions are available inside the spectrometer) you can select them using the software. Removable vacuum-tight covers provide access to the detector and beamsplitter if you want to exchange these components.

VERTEX 70v has five beam outlet ports (on the right, front and left side) and two IR-beam inlet ports (on the right and rear side) allowing the connection of a multitude of optional accessories and/or components like:

• TGA-coupling

• PMA 50 (Polarization Modulation Accessory for VCD and PM-IRRAS) • HYPERION 1000/2000 IR microscope and HYPERION 3000 imaging

microscope with FPA detector (Focal Plane Array detector system) • IMAC module (Imaging Accessory with FPA detector)

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• External sample compartment (XSA)

• HTS-XT module (High Throughput Screening Extension)

• Fiber optic coupling module with MIR or NIR fiber probes for solid and liquid samples

• FT Raman module (e.g. RAM II) • FIR bolometer

• External, water-cooled sources

There is also the possibility to connect several accessories simultaneously (e.g. a water-cooled Hg-arc source at the rear side, the RAM II FT-Raman module at the right side, a fibre optics coupling at the right front side, the HYPERION IR microscope at the left side and a bolometer detector at the front side).

Diagnostic routines help to maintain optimum instrument status and performance. The internal validation unit (IUV) is located inside the spectrometer. It contains standards (test samples) used for the validation and testing of the instrument.

Note: Depending on the spectrometer configuration you have ordered, your spectrometer may not include all options that are described in this manual.

The evacuable VERTEX 70v spectrometer allows measurements under vacuum condi-tions, i.e. unwanted atmospheric interferents (e.g. water vapor or carbon dioxide) are eliminated nearly completely from the spectrometer interior. Evacuating the spectrome-ter is more efficient than purging it or using desiccant cartridges. The result of an opti-mal measurement under vacuum conditions is an IR spectrum in which no H₂O or CO₂ absorptions mask weak spectral features of the sample.

The spectrometer design enables a separate evacuation of the spectrometer compart-ments, i.e. either the complete spectrometer interior (sample compartment plus the opti-cal bench) or only the optiopti-cal bench can be evacuated. Vacuum shutters (so opti-called flaps), which can be equipped with optical or IR windows, allow a ventilation of only the sample compartment in order to preserve the vacuum in the rest of the optics compart-ment during a sample exchange or an accessory installation. Evacuating and venting the sample compartment and/or optics are computer-controlled. Moreover, the spec-trometer is equipped with two pressure sensors providing for the display of the current pressure inside the spectrometer optics and/or sample compartment.

VERTEX 70v is supplied with an efficient vacuum pump that can evacuate the spec-trometer optics within a few minutes. The oil-free vacuum pump prevents the spectrom-eter optics from being contaminated by hydrocarbons.

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N S T A L L A T I O N

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G E N E R A L I N F O R M A T I O N

Unpacking and initial installation of VERTEX 70v is done by Bruker service engineers. The operating company has to provide an installation site that meets the site require-ments described in this chapter. (See also the technical document Installation Require-ments for VERTEX 70v provided by Bruker Optik GmbH in advance.)

This chapter contains a list of the standard as well as the optional spectrometer compo-nents and describes the procedures for connecting the spectrometer:

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to the power supply,

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to a PC,

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to the vacuum pump and

•

to the purge gas supply line, if necessary.

For detailed information about how to install the computer, refer to the PC manual.

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D E L I V E R Y S C O P E

The basic instrument of VERTEX 70v allows upgrading with additional components and/ or accessories. The delivery scope depends on the spectrometer configuration you have ordered.

S t a n d a r d C o m p o n e n t s

The basic instrument includes the following items:

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VERTEX 70v spectrometer (including the user manual)

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Power cord

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PC compatible data system (if desired, the PC can also be provided by the customer)

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Data cable (Cat5, crossover cable for 10Base-T Ethernet standard)

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Purge gas hose (OD: 6mm, length: approx. 5m)

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Tool kit (slot-head screw driver, cross-head screwdriver and hex keys of several sizes, sample preparation tools, 3x spare fuses, IR sensor card, metallic cap shown in fig. 28)

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Delivery Scope

For installing the vacuum pump, the following items are included:

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Vacuum pump (including the user manual)

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Noise reduction hood

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Vibration absorber

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2x flexible metal hoses

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4x hose clamps

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4x sealing rings

O p t i o n a l C o m p o n e n t s

Depending on the ordered spectrometer configuration, the delivery scope can also include following optional components:

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Optional spectrometer components (e.g. optional detectors) and/or accessories

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Optional OPUS software packages (e.g OPUS/STEP) including the corresponding manuals

I n s p e c t i n g t h e P a c k a g i n g

After the receipt of the spectrometer, inspect the packaging for damages. If there are any signs of damage, contact your local shipping representative before opening the shipping box.

Warning: Do not put a spectrometer into operation that shows signs of damage. Failure to do so may result in severe personal injuries and/or property damage.

T r a n s p o r t a t i o n

Due to its weight (about 105kg), VERTEX 70v has to be carried by at least four persons using the supplied transport handles. For transportation purposes, attach these handles properly to the right and left spectrometer side as shown in figure 1 using 12 screws (M5 x 16). Tighten the screws using a hex kex (size 4mm). After having transported the instrument to the desired place, you can remove the transport handles again. Alterna-tively, you can transport the instrument with a fork lifter.

Warning: Due to the high instrument weight, improper transportation can lead to personal injuries and/or spectrometer damage.

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Site Requirements

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S I T E R E Q U I R E M E N T S

S p a c e R e q u i r e m e n t s

The spectrometer dimensions are 85cm (w) x 71cm (d) x 32cm (h). (For exact spec-trometer dimensions refer to appendix D.) At the rear side, the specspec-trometer requires a clearance of at least 25cm (10“). The spectrometer should be placed on a stable and horizontal base. Note that the basic instrument has a weight of about 105kg.

When preparing the installation location for the spectrometer, take into consideration that the mains power supply connection is easily accessible at any time. The mains power supply can be interrupted, for example, either by disconnecting the safety plug or switching off the mains switch on the spectrometer rear side or disconnecting the pri-mary power receptacle.

E n v i r o n m e n t a l R e q u i r e m e n t s

To ensure optimum spectrometer performance and long-term reliability the following environmental conditions are essential:

Temperature Range: 18 - 35 °C (64 - 95 °F)

In case the vacuum pump is operated with installed noise reduction hood ensure the ambient temperature does not exceed 32°C (90°F).

Humidity (non-condensing): 80% (relative humidity)

Temperature variations can impair the results of long-term measurements. Therefore, the temperature variations should be less than 1°C per hour and should not exceed 2°C per day for this type of measurement.

Figure 1: Installing the Transport Handles Transport

Handles

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Site Requirements

V i b r a t i o n

Ideally, the spectrometer should not be installed near vibration sources (e.g. ventilation hoods, air conditioners, motors, elevator etc.) or in rooms with intense floor vibration.

P o w e r S u p p l y

The spectrometer power supply unit automatically adapts to the most common power sources.

Valid voltage range: 100 V AC to 240 V AC Valid frequency range: 50 to 60 Hz

VERTEX 70v is an instrument of the protection class I.

Caution: To avoid personal injury and spectrometer damage, connect the spectrometer only to a socket outlet with earthing contact.

To provide for good data quality and a long spectrometer service life, ensure that the fol-lowing site requirements are met:

•

Do not install the spectrometer near sources of potential inductive electrical interference (e.g. pumps, switching motors, microwave ovens etc.), sources of high energy pulses, and sources that might cause magnetic or radio frequency interference.

•

Do not place devices such as large electric motors, heaters, welding equipment, radio transmitting equipment, units emitting pulsed NMRs, or high powered lasers in close vicinity to the spectrometer. These devices can interfere with the

spectrometer and cause spectrometer malfunction. Ensure that these types of devices are not connected to the same electrical circuit as the spectrometer.

•

If a reliable mains power supply is a problem at your site (caused by brownouts, power surges, frequent thunderstorms, for example), take precautions to ensure an uninterruptible power supply.

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Connecting VERTEX 70v to the Power Supply

C O N N E C T I N G V E R T E X 7 0 V T O T H E P O W E R

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S U P P L Y

P o w e r C o r d

Before connecting the power cord, make sure that the spectrometer is switched off, i.e. the mains switch (B in figure 2) is in the “O” position. Connect the supplied power cord to the primary power receptacle (C in figure 2) as well as to the mains socket outlet. The power cord length should not exceed 3m. Depending on the local conditions, the original power cord may need to be exchanged for a power cord that complies with the standards of the country in question. The power cord must have approbation of at least your local authority, UL for US, CSA for Canada or VDE for Europe. The spectrometer power supply unit automatically adapts to the local voltage and frequency range. (See section Site Requirements.)

Component

A Ethernet port

B Mains switch

C Primary power receptacle (for connecting the power cord)

Figure 2: Spectrometer Rear Side - Connections for Power Supply and PC A

B

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Connecting VERTEX 70v to a PC

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C O N N E C T I N G V E R T E X 7 0 V T O A P C

D a t a C a b l e

The data cable included in the spectrometer delivery scope is a CAT5 crossover cable (labelled “Cross-over”) with two RJ-45 plugs. This cable is only used for the direct con-nection of VERTEX 70v to a computer. If you intend to connect the spectrometer to a network, a different type of cable (i.e. non-crossover, CAT 5 cable for the 10Base-T Eth-ernet standard) is required. (See appendix E.) The data cable length should not exceed 100m (without repeater).

Connect one end of the data cable to the Ethernet port (ETH) (A figure 2) and the other end of the data cable to the RJ-45 socket of the computer network interface card. (For detailed information refer to the computer manual.)

After having set up the data cable connection, turn on the spectrometer using the mains switch. After a few seconds, the spectrometer beeps once and starts a self test. After the initialization has been completed successfully, the “STATUS” LED (figure 10) turns from red to green. Now switch on the computer and the monitor. (For information on how to install the computer and how to set up signal and power cable connections for the computer, monitor etc. refer to the computer manual.)

C o m p u t e r S e t u p

VERTEX 70v and the delivered PC are already configured for the stand-alone opera-tion. The spectrometer IP address is factory-set to 10.10.0.1. In case you have not pur-chased the computer together with the VERTEX 70v spectrometer, you have to assign an appropriate IP address to the computer to which you want to connect the spectrome-ter. For detailed information about how to assign an IP-address to the computer refer to appendix E.

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Connecting VERTEX 70v to the Vacuum Pump

C O N N E C T I N G V E R T E X 7 0 V T O T H E V A C U U M

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P U M P

The attachment flange (NW25 flange) for connecting the vacuum pump is at the spec-trometer rear side. Figure 3 shows the valve block with removed cover.

The vent openings are covered by a plug made from sintered-powder metal which is air-permeable (i.e. the spectrometer can be vented with the plugs installed on the vent opening). (See figure 8.) The plug functions like a filter preventing particles from enter-ing the spectrometer together with the influent air.

Note: For detailed information about the vacuum pump refer to the user manual provided by the vacuum pump manufacturer.

Attachment Flange for the Vacuum Pump

Opening for venting the optical bench

(Note: When purging the spectrometer this port is used as purge gas inlet for the optical bench.

Valve for evacuating the optical bench

Valve for evacuating the sample compart-ment

Figure 3: Valve Block (Spectrometer rear Side)

Opening for venting the sample compart-ment

(Note: When purging the spectrometer this port is used as purge gas inlet for the sample compartment.

Valve for venting the sample compartment Valve for venting the

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Connecting VERTEX 70v to the Vacuum Pump

I n s t a l l a t i o n P r o c e d u r e

•

Remove the valve block cover shown in figure 4 by loosening the two Allen screws using a hex key (size 3mm) and pulling off the cover.

•

Install the supplied sealing ring at the attachment flange. See figure 5.

•

Press the supplied flexible metal hose against the attachment flange (figure 6a) and attach the hose to the flange using the supplied hose clamp (figure 6b). Secure the hose clamp by fastening the wing screw.

Allen Screws Valve Block Cover

Figure 4: Removing the Valve Block Cover

Figure 5: Connecting VERTEX 70v to Vacuum Pump - Step 1

Attachment Flange Sealing Ring

Flexible Metal Hose

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Connecting VERTEX 70v to the Purge Gas Line

During operation, the vacuum pump generates vibrations. In order to prevent these vibrations from being transferred to the spectrometer via the flexible metal hose, the supplied vibration absorber has to be installed between the vacuum pump and the spectrometer. The procedure for connecting the flexible metal hose to the vacuum pump and to the vibration absorber is identical to the procedure described above.

Note: Make sure that the vibrating metal hoses do not come into contact with the table on which the spectrometer is placed.

During the operation, the vacuum pump produces an increased noise level. In order to reduce the noise level install the supplied noise reduction hood over the vacuum pump. For information about the noise reduction hood installation refer to instructions provided by the pump manufacturer.

C O N N E C T I N G V E R T E X 7 0 V T O T H E P U R G E

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G A S L I N E

As an alternative to the vacuum operation, VERTEX 70v can be purged with either dry air or dry nitrogen gas. The spectrometer has two purge gas inlets; one for purging the sample compartment and the other for purging the optical bench. The purge gas inlets are at the spectrometer rear side. See figure 7.

Figure 6: Connecting VERTEX 70v to Vacuum Pump -Step 2

Hose Clamp Wing Screw

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For detailed information about the required purge gas supply conditions refer to chapter Operation, section Purging the Spectrometer.

I n s t a l l a t i o n P r o c e d u r e

Note: In case the spectrometer is evacuated, first vent it before starting the installation procedure. Otherwise, a warning message regarding unstable pressure conditions inside the spectrometer will appear.

•

To connect the spectrometer to the purge gas supply you need a stiff hose with an outer diameter of 6mm. Remove the plug (made from sintered-powder metal) from the purge gas inlet by pressing the lock ring inwards (figure 8) and pulling out the plug. Connect one end of the hose to your supply line for dry air or dry nitrogen gas and insert the other end of the hose into the purge gas inlet for either the sample compartment or optical bench.

•

If you want to purge both the sample compartment and the optical bench, you need a T-shape connecting hose with two hose ends leading to the spectrometer. After having connected the main end of the hose to the supply line, insert one of the other two hose ends into the purge gas inlet for the sample compartment and the other hose end into the purge gas inlet for the optical bench.

Figure 7: Purge Gas Inlets

Purge gas inlet for optical bench.

(Note: In case of vacuum operation - vent opening for venting the optical bench.)

Purge gas inlet for sample compartment.

(Note: In case of vacuum operation - vent opening for venting the sample com-partment.)

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Figure 8: Purge Gas Inlet with removed Plug

Plug Lock Ring

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O

V E R V I E W

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G E N E R A L I N F O R M A T I O N

This chapter describes all relevant external and internal spectrometer components.

Note: The local indications right and left assume that the operator stands in front of the spectrometer. The indications forward and backward refer to the spectrometer front side and rear side, respectively.

Compartment

A Power Supply Connector

B Status Indicator Board

C Electronics Compartment

D Interferometer Compartment

E Detector Compartment

F Sample Compartment

G Laser

H Vacuum Pump Connection Port

I Beam Direction Control Compartment A B C D E F G H I

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External Components

The detector compartment, the interferometer compartment and the beam direction control compartment are not separated from each other but form one compartment. All spectrometer compartments are accessible by removing the corresponding cover.

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E X T E R N A L C O M P O N E N T S

S t a t u s I n d i c a t o r B o a r d

The status indicator board is in the left rear corner of the spectrometer, more precisely, on the electronic compartment cover. (See figure 10.) The color of the LEDs gives a general indication of the operating status of the corresponding spectrometer compo-nent. Moreover, the color of the Vacuum LED indicates the current pressure situation inside the spectrometer compartments (i.e it shows whether a certain compartment is being evacuated/vented just now or is already evacuated/vented). In case one of these LEDs lights up red indicating a spectrometer problem refer to chapter Troubleshooting. This chapter shows possible causes of a problem and provides solutions.

V A C U U M

The color of VACUUM LED depends on the current pressure situation inside the individ-ual spectrometer compartments. The following table explains the meaning of the differ-ent LED colors:

LED is off. Sample compartment and optical bench are vented.

LED flashes green. Sample compartment and optical bench are being either evacuated or vented.

LED lights up green. Sample compartment and optical bench are evacuated. The ultimate vacuum is

achieved.

LED flashes yellow. Sample compartment is being either evacuated or vented. (In case the sample

compartment is already vented, it flashes yellow also when the optical bench is being vented.)

LED lights up yellow. Sample compartment is vented.

LED lights up red. When the spectrometer is being evacuated, but a certain threshold pressure value

is not reached within a certain period of time (i.e. the ultimate vacuum is not achieved). A red VACUUM LED indicates a problem. See chapter Troubleshooting, section Problem - Possible Cause - Solution, subsection Spectrometer problem

indicated by spectrometer status indicator. Figure 10: Status Indicator Board

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. . . . .

External Components L A S E R

The LASER LED lights green when the laser is in operation and the laser signal is OK. The LASER LED lights up red if the laser power is too weak, the laser beam is blocked or if the laser module is defective or out of alignment. (See chapter Troubleshooting, section Problem - Possible Cause - Solution, subsection Spectrometer problem indi-cated by spectrometer status indicator.) This control lamp also lights up red during the spectrometer initialization phase. After the initialization is completed successfully, this LED turns to green.

S T A T U S

A green STATUS LED indicates that the spectrometer is in proper operating condition. The STATUS LED lights up red in case of a spectrometer malfunction or during the ini-tialization phase. After the iniini-tialization is completed successfully, this LED turns to green. (See chapter Troubleshooting, section Problem - Possible Cause - Solution, sub-section Spectrometer problem indicated by spectrometer status indicator.)

S a m p l e C o m p a r t m e n t

Normally, you gain access to the sample compartment from the spectrometer top side by removing the blue cover using the handle. See figure 11a. In exceptional cases, if your measurement accessory requires access from the spectrometer front side (e.g. for exchanging the sample), you can remove the blue front cover by loosening the six Allen screws using a hex key size 3mm. See figure 11b.

Note: When performing measurements under vacuum condition do not forget to reinstall the sample compartment front cover.

The sample compartment dimensions are 25.5cm (w) x 27cm (d) x 16cm (h). For more information about the sample compartment interior refer to chapter Operation, section QuickLock.

Figure 11: a) Sample Compartment Top Cover b) Sample Compartment Front Cover

Allen Screws Sample Compartment Cover Handle

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4

External Components

I R B e a m P o r t s

VERTEX 70v has seven IR beam ports (five outlet ports and two inlet ports) allowing the adaptation of external accessories and/or components (e.g. microscope, TG-IR cou-pling or external light source). The IR beam ports are at the front and rear side as well as at the left and right hand side of the spectrometer. For the exact dimensions of the IR beam port positions refer to appendix D.

IR Beam Ports

A Outlet port for focussed beam (e.g. for connecting a bolometer)

B Outlet port for parallel beam (e.g. for connecting a fiber optic coupling module)

C Inlet port for connecting a light emission source (e.g. Hg source) D Outlet port for parallel beam

E Outlet port for parallel beam (e.g. for connecting a microscope, PMA50, external sample compartment XSA)

F Inlet port for connecting a light emission source (e.g. FT-Raman mod-ule, water-cooled, high-power MIR source)

G Outlet port for parallel beam (e.g. for connecting a microscope) or focussed beam (e.g. for connecting a bolometer)

Figure 12: c) Right Side d) Left Side Figure 12: a) Front Side b) Rear Side

A B

D E F G

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. . . . .

External Components The IR beam ports are vacuum-tight sealed by circular covers. To remove a cover loosen the six Allen screws using a hex key size 3mm. See figure 13.

Note: External accessories are installed by the Bruker service technicians.

S p e c t r o m e t e r R e a r S i d e

Allen Screws

Figure 13: Removing an IR Beam Port Cover

Figure 14: Spectrometer Rear View External Beam Port

Vent Opening/ Purge Gas Inlet

Electronics Panel Mains Switch CAN BUS Port Primary Power Receptacle Attachment Flange

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4

External Components E X T E R N A L B E A M P O R T

The inlet port is used for connecting a light source (e.g. Hg-Source) or an emission sample.

V E N T O P E N I N G / P U R G E G A S I N L E T

Depending on whether you evacuate or purge the spectrometer, these two ports serve different purposes. In case of evacuating the spectrometer these ports serve as vent openings, whereas, when purging the spectrometer the purge gas supply lines are con-nected to these ports. (For detailed information about installing the purge gas connec-tion refer to chapter Installaconnec-tion.)

E L E C T R O N I C S P A N E L

On the electronics panel are a number of ports (e.g. Ethernet port), the reset button as well as LEDs indicating, for example, the status of the interferometer. For a detailed description of the electronics panel refer to appendix F.

M A I N S S W I T C H A N D P R I M A R Y P O W E R R E C E P T A C L E

The mains switch is used to turn the spectrometer on and off. The power supply socket is used to connect the power cord to the spectrometer.

C A N B U S P O R T

The CAN bus port is primarily used to connect external automated units to the spec-trometer. For more information refer to appendix F.

A T T A C H M E N T F L A N G E F O R V A C U U M P U M P

The vacuum pump can be connected to this attachment flange (NW25) using the sup-plied sealing ring, flexible metal hose and hose clamp. (For detailed information about how to connect the vacuum pump to the spectrometer refer to chapter Installation.)

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. . . . .

Internal Components

. . . .

I N T E R N A L C O M P O N E N T S

The following figure identifies only the most important internal components and their location inside the spectrometer.

Component

A RockSolid interferometer (permanently aligned) B DigiTect Detectors

C Sample holder for transmission measurements (exchangeable for other optional accessories with QuickLock baseplate)

D HeNe laser

E Two beamsplitters storage positions (optional) F Beamsplitter (operation position)

G Optional NIR source (operating position) H MIR source (operating position)

I QuickLock mechanism for accessories (including connectors)

Figure 15: Internal Spectrometer Components B D E A F G H I C

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4 L i g h t S o u r c e

The basic instrument is equipped with a MIR source (H in figure 15). The MIR light source is a globar (i.e. an U-shaped silicon carbide piece) that emits mid-infrared light. Apart from the standard air-cooled MIR source, the following optional sources are avail-able:

•

VIS/NIR source (tungsten halogen lamp), installed in the spectrometer (G in figure 15), air-cooled

•

FIR source (mercury lamp), connected externally to the spectrometer, water-cooled

•

UV/VIS/NIR source (tungsten lamp), connected externally to the spectrometer, water-cooled

•

UV source (deuterium lamp), connected externally to the spectrometer, air-cooled

•

High power MIR source (globar), connected externally to the spectrometer, water-cooled

All external sources can be connected to one of the two inlet ports (C in figure 12b or F in figure 12c). For the FIR source (mercury lamp), the preferred connection port is the inlet port at the spectrometer rear side, C in figure 12b.

D e t e c t o r

The basic spectrometer configuration is equipped with a DigiTect DLaTGS detector with integrated preamplifier. This detector package contains an analog-to-digital-converter that converts the analog signal from the detector directly into a digital signal. This digital signal is transmitted to the data processing electronics unit of the spectrometer. The standard detector is a pyroelectric DLaTGS detector which covers a spectral range from 12,000 to 250cm-1, operates at room temperature and has a sensitivity of D*>4x108 cm Hz1/2 W-1.

Apart from the standard detector, there is a large number of optional detectors. All detectors are mounted on dovetail slides which allow an easy exchange. The following optional detectors are available:

Detector Spectral Range (cm-1) Sensitivity Operating Temperature Mid-Infrared DLaTGS with KBr window 12,000 - 250 _D*>4x108_{cm Hz}1/2_W-1 Temperature-sta-bilized DLaTGS with CsI

window

12,000 - 160 _D*>4x108_{cm Hz}1/2_W-1 _{Room temperature}

MCT narrow band, with BaF₂ window

CAUTION - HARMFUL!

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. . . . .

Warning: Some detectors are equipped with windows of which the material is harmful or (very) toxic. During normal spectrometer operation, these materials do not pose a health risk. However, should these windows break caused by mechanical impact, be extremely careful. Avoid generating dust. These materials are harmful or toxic if swallowed or inhaled. Also avoid skin and eye contact.

MCT mid band, with ZnSe window CAUTION - TOXIC! 12,000 - 600 _D*:>2x1010_{cm Hz}1/2 _W-1 Liquid N₂ cooled MCT broad band, with KRS-5 window CAUTION - TOXIC! 12,000 - 420 _D*:>5x109_{cm Hz}1/2_W-1 _{Liquid N}₂_cooled Photovoltaic MCT, with BaF₂window

CAUTION - HARMFUL!

12,000 - 850 _D*:>2x1010_{cm Hz}1/2 _W-1 Liquid N₂ cooled

MCT/InSb Sandwich, with ZnSe window

CAUTION - TOXIC!

10,000 - 600 _D*:>2x1010_{cm Hz}1/2_W-1 _(MCT)

D*:>1.5x1011cm Hz1/2W-1(InSb)

Liquid N₂ cooled

Near-Infrared

InSb 10,000 - 1,850 _D*:>1.5x1011_{cm Hz}1/2 _W-1 _{Liquid N}₂_cooled

InSb with cold filter 10,000 - 3,100 _D*>5x1011_{cm Hz}1/2 _W-1 _{Liquid N}₂_cooled

Ge Detector (Raman) 11,750 - 5,900 _NEP<10-15_{W Hz}-1/2 _{Liquid N}₂_cooled

InGaAs Diode 12,800 - 5,800 _NEP:<2x10-14_{W Hz}-1/2 _{Room temperature}

InGaAs Diode 12,800 - 4,000 _NEP:<2x10-13_{W Hz}-1/2 _{Peltier cooled}

Ge Diode 15,000 - 5,300 _NEP:<5x10-12_{W Hz}-1/2 Room temperature Far Infrared

DLaTGS with PE win-dow

700 - 10 _D*>4x108_{cm Hz}1/2_W-1 _{Room temperature}

Silicon Bolometer 600 - 10 _NEP<10-13_{W Hz}-1/2 _{Liquid He cooled}

Visible & UV

Silicon Diode 25,000 - 9,000 _NEP:<10-14_{W Hz}-1/2 _{Room temperature}

GaP Diode 33,000-18,000 _{No NEP available} Room temperature

Detector Spectral

Range (cm-1) Sensitivity

Operating Temperature

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4 B e a m s p l i t t e r

The standard KBr beamsplitter covers a spectral range from 8000 to 350cm-1. Apart from the standard beamsplitter, there are also optional beamsplitters. They allow data acquisition in wavelength ranges other than MIR (standard) when used in conjunction with the appropriate light source and detector. Note that the combination of light source, detector, beamsplitter and sample compartment window material defines the IR mea-surement range. The following optional beamsplitters are available:

Caution: The beamsplitter material CaF₂ is harmful if inhaled or swallowed. Avoid also skin and eye contact.

L a s e r

VERTEX 70v is equipped with a HeNe laser (D in fig. 15) It emits red light with a wave-length of 633nm. The rated power output is 1mW. The laser controls the position of the moving interferometer mirror (also called ’scanner’) and is used to determine the data sampling positions. The monochromatic beam produced by the HeNe laser is modu-lated by the interferometer to generate a sinusoidal signal. For information about how to replace a defective laser module, refer to chapter Maintenance and Repair.

I n t e r f e r o m e t e r

VERTEX 70v is equipped with a high stability interferometer with ROCKSOLID perma-nent alignment. The ROCKSOLID interferometer incorporates dual retroreflecting cube corner mirrors in pendulum arrangement. The high throughput design ensures the high-est possible signal-to-noise ratio.

Beamsplitter Spectral Range (cm-1) Color Coding of the Beamsplitter Handle Mid-Infrared

KBr (standard) 7,500 - 370 red

KBr (broad band) 10,000 - 400 red

Csl 5,000 - 210 red Near-Infrared CaF₂ CAUTION - HARMFUL! 15,500 - 1,200 black Visible & UV

Quartz VIS/UV 25,000 - 9,000 white

Far-Infrared

Multilayer (far IR) 680 - 30 nickel-plated

Mylar 25µm 120 - 20 nickel-plated

Mylar 50µm 50 - 10 nickel-plated

Solid state 600 - 30 *

* limited to a spectral resolution of 0.5cm-1

nickel-plated Alignment Tool

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. . . . .

Optical Path

. . . .

O P T I C A L P A T H

The beam path shown in figure 16 ist the beam path of the standard spectrometer con-figuration.

D1 Standard detector

D2 Optional detector

BMS Beamsplitter

APT Aperture wheel

OPF Optical filter wheel

IN1 ... IN2 Beam inlet port 1 ... 2 OUT1 ... OUT5 Beam outlet port 1 ... 5 Figure 16: VERTEX 70v - Optical Path

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4

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. . . .

O

PERATION

5

. . . .

G E N E R A L I N F O R M A T I O N

After the spectrometer has been installed and connected to the power supply, the PC, and the vacuum pump, the spectrometer is ready for operation. VERTEX 70v is com-pletely computer-controlled, i.e. operating the spectrometer (e.g. selecting the corre-sponding optical components) performing a measurement and evacuating/venting the spectrometer is done using the spectroscopic software OPUS.

This chapter describes mainly the spectrometer related aspects of the operation. For detailed information about the OPUS software refer to the OPUS Reference Manual. The OPUS manual “Getting Started” explains step by step how to perform the first mea-surement after the spectrometer has been set up.

The standard spectrometer configuration is designed for measurements in the mid infra-red region. Optionally, the spectral region can be expanded by substituting the installed MIR components (source, detector, beamsplitter and sample compartment windows, if available) for the corresponding optical components that allow measurements in the far or near infrared as well as in the visible or ultraviolet region. (For information about the replacement procedure of these optional components refer to the corresponding sec-tions in this chapter and in chapter Maintenance and Repair.)

. . . .

S W I T C H I N G V E R T E X 7 0 V O N A N D O F F

G e n e r a l I n f o r m a t i o n

The spectrometer is turned on and off using the mains switch at the spectrometer rear side (figure 14). After having switched on the spectrometer, it starts booting. The boot process takes about 30 seconds. As soon as this process is completed successfully, the STATUS LED (figure 10) turns from red to green.

After having switched on the spectrometer wait at least ten minutes before starting the first measurement. This allows for the electronics and the light source to stabilize ther-mally.

Caution: After having switched the spectrometer off, wait at least 30 sec-onds before switching the spectrometer on again. This measure avoids peaks in the initial current which could lead to fuse blowing and/or damaging the power switch.

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5

Switching VERTEX 70v On and Off

S w i t c h - o n P r o c e d u r e

To put the spectrometer into operation again, proceed as follows:

1 Switch on the PC.

2 Switch on the spectrometer. The spectrometer begins to start up.

Note: After the spectrometer initialization is completed successfully, the STATUS LED turns to green. Now the spectrometer is ready for operation again.

3 Connect the the vacuum pump to the power supply.

Note: For information about how to operate the vacuum pump refer to the supplied user manual of the vacuum pump manufacturer.

S w i t c h - o f f P r o c e d u r e

Ideally, the spectrometer should uninterruptedly be kept under vacuum, even during times of nonuse. If, however, the circumstances require a switching-off of the vacuum pump and/ or the spectrometer the following procedure is recommended:

1 Evacuate the optical bench.

2 As soon as the final pressure is reached, switch off the spectrometer.

Note: The evacuation will take about 5 minutes. In the electroless

spectrometer state, all valves (for venting as well as for evacuating the spectrometer) are closed.

3 Disconnect the vacuum pump from the power supply.

In this state, the spectrometer interior is isolated from the laboratory environment and the optical spectrometer components are protected against air humidity and they are no longer current-carrying.

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. . . . .

QuickLock

. . . .

Q U I C K L O C K

The sample compartment is equipped with a locking mechanism, called QuickLock, for positioning and locking different measurement accessories. Therefore, you can use only accessories that are mounted on a QuickLock baseplate. The QuickLock mecha-nism enables a solid lock even for heavy and bulky accessories and allows a quick, easy and reproducible positioning of the measurement accessories in the sample com-partment.

When you insert and lock the accessory, all connections (purge gas connection and electrical connection) are established and the accessory is automatically recognized by the application software OPUS. This software feature is called AAR - Automatic Acces-sory Recognition. In addition, the recommended measurement parameters are selected automatically, provided that you have already stored the parameters for the accessory in question. (See OPUS Reference Manual.)

The QuickLock mechanism also allows purging the sample compartment with dry air or nitrogen gas. The purge gas enters the sample compartment via the gas diffusor (figure 18). Purge gas connection port QuickLock locking device Electronic connectors

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5

QuickLock

T o i n s e r t a n a c c e s s o r y w i t h Q u i c k L o c k b a s e p l a t e :

1 Hold the accessory with the QuickLockbaseplate front edge slightly tilted upwards. Then, gently push the electrical connectors of the baseplate against their counterpart of the QuickLock holder. Put the baseplate down. Ensure that the baseplate is horizontally aligned to the QuickLock holder.

2 Gently press the front edge of the baseplate downward until it snaps into place. To facilitate the insertion of the accessory, press the release button outside the sample compartment. (See figure 17b.)

T o r e m o v e a n a c c e s s o r y w i t h Q u i c k L o c k b a s e p l a t e :

1 Press the QuickLock release button outside the sample compartment. (See figure 17b.)

2 While pressing the QuickLock release button, lift the front edge of the QuickLock baseplate until the baseplate snaps free.

3 Carefully lift the accessory off the QuickLock holder to avoid damages to the electrical connectors at the baseplate rear side.

Figure 18: Accessory with QuickLock Baseplate

Purge gas diffusor

Electronic connectors for AAR and CAN bus

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. . . . .

Automatic Accessory Recognition

. . . .

A U T O M A T I C A C C E S S O R Y R E C O G N I T I O N

As soon as an accessory is locked into the QuickLock holder, the OPUS/AAR software (Automatic Accessory Recognition) starts and recognizes automatically the accessory in question, provided you have activated the AAR function in the OPUS software. (For information about how to activate the AAR function refer to the OPUS reference man-ual, OPUS manual part Automatic Accessory Recognition“).

The OPUS/AAR software identifies the accessory, performs several tests, adapts the measurement parameters and opens the Measurement dialog window to start a mea-surement. If the automatic accessory recognition has been completed successfully, OPUS displays a corresponding message.

Each time you start OPUS, the AAR program checks whether an accessory is installed into the sample compartment. If AAR detects an accessory, the corresponding dialog box is displayed. It also appears when the accessory is substituted by another one.

Note: When installing a new accessory for the first time, it is not yet registered so that the OPUS/AAR software can not recognize it. In this case, you first have to register the new accessory in question. (See OPUS Reference Manual.)

. . . .

P E R F O R M I N G A M E A S U R E M E N T

The measurement procedure described in the following refers exclusively to measure-ments under vacuum conditions. In case you want to perform a measurement not under vacuum ignore the steps regarding evacuating and venting the spectrometer.

•

Specify the measurement parameters in the OPUS programme. To do this, select in the OPUS Measure menu the Advanced Measurement function and select or enter the corresponding parameter values. (The standard parameter values are listed in appendix C.)

•

Evacuate the spectrometer as described in the following section. (Wait until the ultimate vacuum is achieved.)

•

Acquire a background spectrum without the sample in the sample compartment by clicking in OPUS on the Background Single Channel button. (See figure 19.)

•

Vent the sample compartment as described in the following section.

•

Put the sample in the sample compartment. (For information about how to install a QuickLock accessory into the sample compartment refer to the section QuickLock in this chapter. For information about sample preparation refer to appendix G.)

•

Evacuate the sample compartment again. (Wait until the ultimate vacuum is achieved.)

•

Acquire a sample spectrum by clicking in OPUS on the Sample Single Channel button (figure 19) and calculate the ratio (transmittance spectrum).

Note: Use the same parameter values for the background and the sample measurement. Ensure that both measurements are performed under identical ambient conditions.

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5

Evacuating and Venting the Spectrometer

For detailed information about OPUS functions for data acquisition, manipulation and evaluation refer to the OPUS Reference Manual.

E V A C U A T I N G A N D V E N T I N G T H E

. . . .

S P E C T R O M E T E R

VERTEX 70v is primarily designed for vacuum operation, but it can be purged as well. To activate the vacuum mode, select in the OPUS Measure menu the Optic Setup and Service function. Click on the Devices/Options tab and make sure that the Purge Mode check box is not ticked off. See figure 20.

Figure 19: OPUS Measurement Dialog Window

Figure 20: Activating the Vacuum Mode

With this checkbox being deactivated, the vacuum mode is activated.

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. . . . .

Evacuating and Venting the Spectrometer The flaps and the venting and evacuating valves are controlled automatically via the OPUS software. So evacuating and venting the sample compartment and/or optical bench is done using the OPUS software. The corresponding buttons are at the Basic page of the Measurement dialog window. See figure 21.

Let us assume the following initial situation: both the sample compartment and the opti-cal bench are vented. In this case, it is not possible to evacuate only the sample com-partment. (The evacuation of only the sample compartment is not possible as in this case the pressure difference between the sample compartment and the optical bench would damage the flaps, i.e. the flaps are not designed for such an operation condition.) So, clicking on either button effects the evacuation of both compartments. The evacua-tion process is indicated by the message Sample / Optics Evacuating that appears in the fields below the buttons. The progress of the evacuation is shown by the perma-nently updated pressure readings in the lower fields. See figure 22.

Note: After you have clicked on a button, the labeling of this button

changes immediately showing the action that can be performed next (i.e. Evacuate... turns to Vent... and versa vice).

Current state in the individual compart-ments including the current pressure reading

Command that can be executed next by clicking on this button.

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5

As soon as the evacuation process is completed, the message Sample / Optics Evacu-ated appears in the lower fields. See figure 23.

Note: If the sample compartment is evacuated you can not open it.

Note: To prevent OPUS from starting a measurement while the

spectrometer is being evacuated or vented proceed as follows: Click in the Measurement dialog window on the Optic tab and select in the

Optical bench ready drop-down list the option Pressure stable. See

figure 24.

Figure 22: Optical bench and sample compartment are being evacuated.

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. . . . .

When both compartments are evacuated you can vent the sample compartment sepa-rately (for example, if you want to open the sample compartment in order to exchange the sample) by clicking on the Vent Sample button.

Note: When both compartments are evacuated, venting only the optical bench is not possible as the pressure ratio inside the spectrometer would damage the flaps. For safety reasons, the instrument does not perform this operation. In this case, clicking on the Vent Optics button effects the ventilation of the sample compartment as well. This precaution prevents the instrument from being operated wrongly.

Figure 24: Defining the Measurement Start Precondition

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5

Optimizing the Vacuum Operation of the Spectrometer

O P T I M I Z I N G T H E V A C U U M O P E R A T I O N O F

. . . .

T H E S P E C T R O M E T E R

G e n e r a l I n f o r m a t i o n

To get optimum measurement results under vacuum conditions, there are some aspects that need to be taken into consideration:

•

The thermal conditions in an evacuated optics bench and in a purged optics bench are completely different, i.e., under vacuum there is no thermal conduction at all due to the lack of the purge gas. This aspect has consequences on the

reproducibility of the measurement results.

•

Water molecules are very polar. Due to this property, they tend to stick at the inner wall of the optics compartment. For this reason, it takes time to get the water vapor pumped off completely.

The purpose of the following advice is to help you in achieving optimum measurement results.

R e p r o d u c i b i l i t y o f t h e R e s u l t s

After having evacuated the spectrometer, it is highly recommended that you allow the spectrometer to stabilize long enough. An optimally stabilized spectrometer is able to achieve an extreme high 100%-line stability in the sub-%-level with the standard optical components designed for MIR measurements. (Note: A precondition is that the room temperature does not vary by more than 1°C per hour and 2°C per day. Typically, this condition can be fulfilled in an air-conditioned environment.)

R e c o m m e n d a t i o n s :

•

For demanding experiments, a stabilization period of at least 4 hours is

recommended. After this period, the maximum instrument stability is achieved.

•

For non demanding experiments, a stabilization time of 0.5 hour is sufficient.

•

During a long-term experiment, it is recommended to repeat the background measurement in regular interval, at least every hour.

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. . . . .

R e s i d u a l W a t e r V a p o r

Longer evacuation times will further reduce the residual water vapor concentration inside the spectrometer:

Note: Besides the necessity of a water vapor concentration being as low as possible, there is another aspect regarding water vapor you have to take into consideration: The water vapor line intensity in the sample spectrum does not depend on the absolute residual water vapor concentration in the spectrometer but on the different water vapor concentrations during the background and the sample measurement. Therefore, it is of crucial importance that the residual water vapor concentration is (nearly) identical during both the background measurement and the sample measurement.

E v a c u a t i o n T i m e

As mentioned above, water molecules are very polar. Due to this property, they tend to stick at the inner wall of the optics compartment, even under vacuum. For this reason, a long evacuation time is recommended. Ideally, the evacuation of the spectrometer should not be interrupted overnight. This action will further reduce the residual water vapor content.

E v a c u a t i o n P r o c e d u r e

Before acquiring a background spectrum, simulate a sample exchange in the same way as you will do it later for the ’real’ sample measurement:

1 Vent the sample compartment.

2 Afterwards, evacuate the sample compartment for about 5 to 10 minutes. (An evacuation time longer than 10 minutes is not necessary because after that period, the final pressure of < 0.2hPa (< 0.2mbar) will be achieved.)

Note: As soon as the pressure falls below < 1hPa, the message Sample

Evacuated, including the current pressure value, is displayed in the Measure dialog window (figure 26). The achievement of the final

pressure is also indicated by the VACUUM LED at the spectrometer top side, i.e. this LED lights green.

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5

Important Note:The evacuation times before the background measurement and before the sample measurement have to be more or less identical. To ensure reproducible evacuation times, specify in OPUS a Delay before Measurement. See the figure 27. 3 Acquire a single channel background spectrum.

4 Afterwards, vent the sample compartment and place the sample in the sample compartment.

5 Evacuate sample compartment for about 5 to 10 minutes.

6 Acquire a single channel sample spectrum.

Figure 26: OPUS dialog window Measurement - page Basic

Current state inside the individual compartments, including the current pres-sure reading

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. . . . .

Purging the Spectrometer

Note: Take into account that the intensity of the water vapor band in the sample spectrum does not depend on the absolute residual water vapor concentration but results from a water vapor concentration difference during the background and the sample measurement.

With the above described operation conditions and a spectral resolution of 4cm-1, typi-cally a residual water vapor band intensity in the range of significantly less than 0.1%T can be achieved.

. . . .

P U R G I N G T H E S P E C T R O M E T E R

G e n e r a l I n f o r m a t i o n

Purging the spectrometer is not necessarily required, especially when you perform measurements under vacuum conditions. However, if the spectrometer is not evacu-ated, purging is recommended, especially when you frequently open the compartment covers (e.g. due to a detector or beamsplitter replacement or a sample substitution) or if the ambient air humidity content is too high because this measure reduces the level of water vapor, CO₂ or other components of the ambient air inside the spectrometer.

Note: Water vapor, CO₂ and other atmospheric contaminants cause

unwanted absorption. Therefore, open the sample compartment, the detector compartment and/or the interferometer compartment only if necessary in order to prevent water vapor, CO₂or other contaminants from entering the above mentioned compartments.

Figure 27: OPUS Measurement dialog

Specifying the measurement delay time