3.3.1 Optical Emission Spectroscopy (OES)
In the OES technique, electrons in the sample emit light which is converted into spectral patterns or a spectrum. The emission spectrum of a chemical element or compound is the spectrum of frequencies of electromagnetic radiation emitted by the element‘s atoms or the compound‘s molecules when returned to a lower energy state [25]. Quantitative and qualitative analysis of the material composition are obtained by the measurement of the intensity of the peaks in the spectrum, since it is different for each element in the periodic table. The quantity plotted energy units, is the wavelength times the energy per unit wavelength and thus accurately represents the amount of energy at any wavelength. The OES device used to obtain the emission spectrum is the DH-2000 Spectrometer (Ocean Optics, Inc. USA) combined with Deuterium Tungsten Halogen Light Sources and a DH- 2000 fiber optic cable. It combines the continuous spectrum of deuterium and tungsten halogen light sources in a single optical path. The combined-spectrum light source produces a powerful and stable output from 215 to 2000 nm.
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3.3.2. Schlieren Imaging
Schlieren imaging with a field view of 20 cm has been used to observe the patterns of perturbation in the neutral gas density (change in refractive index) due to the interaction of the helium gas with ambient air as it exits the capillary and their interaction with the substrate. This was carried out with a z-configuration system [26] similar to that already used on the microjet system [27] utilising two parabolic mirrors, a light source (continuous xenon arc lamp) and a Photron Fastcam APX RS model high-speed video camera running Photron PFV (Photron Fastcam Viewer) software with a 1 ms shutter speed.
3.3.3 2D Optical ICCD Imaging
Fast imaging was done in order to study the temporal and spatial evolution of the microdischarge using an ICCD camera (Andor DH520). A delay generator (DG645 Stanford Research Systems) was used to generate a pulse width of 100 ns to trigger the ICCD camera. Time-resolved and time-averaged images were obtained over eight (8) ac cycles. A 50 ns exposure time was used for imaging of the microchannel and the plasma bullet evolution. A time resolution of a few milliseconds was used for the observation of the general plasma plume structure.
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References
1. R. Wiesendanger, Scanning Probe Microscopy and Spectroscopy, (Cambridge: Cambridge University Press, 1994).
2. Gerd Binnig and Heinrich Rohrer received the Nobel prize for Physics in 1986 for their invention of the scanning tunneling microscope. See also: (a) Binnig G.; Rohrer, H. Helvetica Physica Acta 1982, 55, 726; (b) Binnig, G.; Rohrer, H.; Gerber, Ch.; Weibel, E.1982,
Phys. Rev. Lett. 1982, 49, 57.
3. Miles, M. J. in Characterization of Solid Polymers; New Techniques and Developments Spells, S. J. (Ed.), Chapman & Hall, London, UK, 1994.
4. R. D. Piner, J. Zhu, F. Xu, S. Hong, and C.A. Mirkin, Science 283, 661 (1999). 5. Y. Xia and G.M. Whitesides, Langmuir 13, 2059 (1997)
6. Schönherr, H. Ph.D. Thesis University of Twente, Enschede, The Netherlands, 1999, ISBN 90 365 1347 2.
7. Baty, A. M.; Leavitt, P. K.; Siedlecki, C. A.; Tyler, B. J.; Suci, P. A.; Marchant, R. E.; Geesey, G. G. Langmuir 1997, 13, 5702.
8. Ortega-Vinuesa, J. L.; Tengvall, P.; Lundström, I. Thin Solid Films 1998, 324, 257 9. Ortega-Vinuesa, J. L.; Tengvall, P.; Lundström, I. J. Colloid Interface Sci. 1998, 207, 228;
10. Lin, J. N.; Drake, B.; Lea, A. S.; Hansma, P. K. Langmuir 1990, 6, 509.
11. Baty, A. M.; Leavitt, P. K.; Siedlecki, C. A.; Tyler, B. J.; Suci, P. A.; Marchant, R. E.; Geesey, G. G. Langmuir 1997, 13, 5702.
12. Shibata-Seki, T.; Masai, J.; Ogawa, Y.; Sato, K.; Yanagawa, H. Appl. Phys. A 1998,
51
13. Chan, C.-M. Polymer surface modification and characterization, Hanser/Gardner Publications, Inc., Cincinnatti, OH, 1994
14. XPS was developed by Professor Kai Siegbahn and his collaborators at the University of Uppsala. For his discovery he received the Nobel prize in 1981. See also: a) Siegbahn, K.; Nordling, C.; Fahlman, R.; Hamrin, K.; Hedman, J.; Johansson, T.; Bergmark, T.; Karlsson, S.-E.; Lindgren, I.; Lindberg, B. ESCA: Atomic, Molecular, and Solid State Structure Studied by Means of Electron Spectroscopy, Nova Acta Regiae Sco. Sci.Upsaliensis, Ser. IV, Vol. 20, Almqvist and Wiksells, Stockholm, 1967; (b) Siegbahn, K.; Nordling, C.; Johansson, G.; Hedman, J.; Heden, P. F.; Hamrin, J.; Gelius, U.; Bergmark, T.; Werme, L. O.; Manne, R.; Baer, Y. ESCA Applied to Free Molecules, North-Holland,Amsterdam, 1969.
15. P. Weightman, Phys. Scr. 1992, T41, 27
16. S. Diplas, G. Shao, S.A. Morton, P. Tsakiropoulos, J.F. Watts, Intermetallics 7 (1999) 937.
17. S. Diplas, J.F. Watts, S.A. Morton, G. Beamson, P. Tsakiropoulos, D.T. Clark, J.E. Castle, J. Electron Spectrosc. Relat. Phenom. 113 (2001)153.
18. S. Diplas, J.F. Watts, P. Tsakiropoulos, G. Shao, G. Beamson, J.A.D. Matthew, Surf. Interface Anal. 31 (2001) 734.
19. K. Kobayashi, Nucl. Instrum. Meth. Phys. Res. A 547 (2005) 98. 20. Anand, M.; Cohen, R. E.; Baddour, R. F. Polymer 1981, 22, 361.
21. (a) d‘Agostino, R. Plasma Deposition, Treatment and Etching of Polymer Films, Acadamic Press, Inc.: San Diego, CA, 1990; (b) Zisman, W. A. Contact Angle-Wettability& Adhesion, Gould, R. F. (Ed.); Am. Chem. Soc., Washington, D.C.,1964.
22. (a) Ho, C.-P.; Yasuda, H. J. Biomed. Mater. Res. 1988, 22, 919; (b) Inagaki, N; Tasaka, S.; Kawai, H.; Kimura, Y. J. Adhesion Sci. Technol. 1990, 4, 99.
52
23. Gengenbach, T. R.; Vasic, Z. R.; Chatelier, R. C.; Griesser, H. J. J. Polym. Sci.: Part A: Polym. Chem. 1994, 32, 1399; (b) Gengenbach, T. R.; Griesser, H. J. Surf. Interface Anal.1998, 26, 498; (c) Gengenbach, T. R.; Chatelier, R. C.; Griesser, H. J. Surf. Interface Anal. 1996, 24, 271; (d) Gengenbach, T. R.; Chatelier, R. C.; Griesser, H. J. Surf. Interface Anal. 1996, 24, 611; (e) Gengenbach, T. R.; Griesser, H. J. J. Polym. Sci.: Part A: Polym. Chem. 1999, 37, 2191; (f) Gengenbach, T. R.; Griesser, H. J. J. Polym. Sci.Part A: Polym. Chem. 1998, 36, 985; (g) Gengenbach, T. R.; Griesser, H. Polymer 1999, 40, 5079; (h) Boenig, H. V. Fundamentals of Plasma Chemistry and Technology, Technomic Publishing Co., Inc.: Lancaster, PA, 1988; (i) Yasuda, H. K. J. Macromol.Sci.-Chem. 1976, A10, 383.
24. a) Yasuda, H.; Sharma, A. K.; Yasuda, T. K. J. Polym. Sci. Polym. Phys. Ed. 1981, 19, 285; (b) Yasuda, T.; Okuno, A. K.; Yoshida, K.; Yasuda, H. J. Polym. Sci. Polym. Phys. Ed. 1988,
26, 1781; (c) Yasuda, T.; Yoshida, K.; Okuno, T.; Yasuda, H. J. Polym. Sci. Polym. Phys. Ed.
1988, 26, 2061; (d) Kennedy, V. O. J. Coating Technol. 1988, 60, 37, (e) Brennar, W. J.; Feast, W. J.; Munro, H. S.; Walker, S. A. Polymer 1991, 32, 1527 (f) van Damme, H. S.; Hogt, A. H.; Feijen, J. J. Colloid Interface Sci. 1986, 114, 167 (g) Owen, M. J.; Gentle, T. M.; Orbeck, T.; Williams, D. E. in Polymer Surface Dynamics, Andrade, J. (Ed.), Plenum Press, New York, 1988. 25. Allen, C.W. Astrophysical Quantities, 3rd edition, 1973, p. 109, 172.
26. Merzkirch ,Flow Visualization (New York: Academic) 1987,Chapter 3
27. J.-S. Oh, O. T. Olabanji, C. Hale, R. Mariani, K. Kontis, J. W. Bradley, J. Phys. D, Appl. Phys. 2011,15, 155206
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