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Raman Measurements on Graphite Modified by High Power Laser Irradiation 1

Published online by Cambridge University Press:  25 February 2011

J. Steinbeck ,
G. Braunstein ,
M.S. Dresselhaus ,
B.S. Elman  and
T. Venkatesan
J. Steinbeck
Affiliation:
Massachusetts Institute of Technology, Cambridge, MA
G. Braunstein
Affiliation:
Massachusetts Institute of Technology, Cambridge, MA
M.S. Dresselhaus
Affiliation:
Massachusetts Institute of Technology, Cambridge, MA
B.S. Elman
Affiliation:
GTE Research Laboratory, Waltham, MA
T. Venkatesan
Affiliation:
Bell Communications Research, Murray Hill, MA
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Abstract

The behavior of highly anisotropic materials under short pulses of highpower laser irradiation has been studied by irradiating highly orientedpyrolytic graphite (HOPG) with 30 nsec Ruby-laser pulses with energydensities between 0.1 and 5.0J/cm2. Raman spectroscopy has beenused to investigate the laser-induced modifications to the crystallinestructure as a function of laser energy density of the laser pulse. A Ramanmicroprobe was used to investigate the spatial variations of thesenear-surface regions. The irradiation of HOPG with energy densities above ~ 0.6J/cm2 leads to the appearance of the ~ 1360 cm-1disorder-induced line in the first order Raman spectrum. The intensity ofthe ~ 1360cm-1 line increases with increasing laser energydensity. As the energy density of the laser pulse reaches about 1.0J/cm2, the ~ 1360cm-1 line and the ~ 1580cm-1 Raman-allowed mode broaden and coalesce into a broadasymmetric band, indicating the formation of a highly disordered region,consistent with RBS-channeling measurements. However, as the laser energydensity of the laser pulses is further increased above 3.0J/cm2,the two Raman lines narrow and can again be resolved suggestinglaser-induced crystallization. The Raman results are consistent with highresolution electron microscopy observations showing the formation ofrandomly oriented crystallites. Raman Microprobe spectra revealed threeseparate regions of behavior: (i) an outer unirradiated region where thematerial appears HOPG-like with a thin layer of material coating thesurface, (ii) an inner irradiated region where the structure is uniform, butdisordered, and (iii) an intermediate region between the other regions wherethe structure is highly disordered. The changes in structure of the innerregion are consistent with the behavior observed with RBS and conventionalRaman spectra. The identification of an amorphous carbon-like layer on theouter region is consistent with a large thermomechanical stress at thegraphite surface, introduced by the high power laser pulse, and known tooccur in metals.

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Footnotes

1

The MIT authors acknowledge NSF Grant #DMR 83-10482 for the support oftheir portion of the work.

References

REFERENCES

[1] Venkatesan, T., Jacobson, D.C., Gibson, J.M., Elman, B.S., Braunstein, G., Dresselhaus, M.S. and Dresselhaus, G., Phys. Rev. Lett.53, 360,(1984).Google Scholar
[2] Clarke, R. and Uher, C., High Pressure Properties of Graphite and its Intercalation Compounds, Dept. of Physics, University of Michigan, Ann Arbor, Michigan, 1984.Google Scholar
[3] Gold, J.S., Bassett, W.A., Weathers, M.S., and Bird, J.M., Science, 225, 921, (1984).Google Scholar
[4] Musal, H.M., Thermomechanical Stress Degradation of Metal Mirror Surfaces Under Pulsed Laser Irradiation, NBS-SP-568, pp. 159.Google Scholar
[5] Poate, J.M., Foti, G., Jacobson, D.C., Surface Modification and Alloying by Laser, Ion, and Electron Beams, Plenum Press, New York, 1983.Google Scholar
[6] Mukherjee, K., Mazumder, J., Lasers in Metallurgy, proceedings of a symposium by the Physical Metallurgy and Solidification Committees of The Metallurgical Society of AIME, 1981.Google Scholar
[7] Solin, S.A. and Kobliska, R.J., Proceeding of the 5th International Conference on Amorphous and Liquid Semiconductors,(Taylor and Francis, London,1974); N. Wada, P.J. Gaczi, and S.A. Solin, J. Non-Cryst. Solids 35 and 36, 543 (1980).Google Scholar
[8] Elman, B.S., Dresselhaus, M.S., Dresselhaus, G., Maby, E.W., Mazurek, H., Phys. Rev. B24, 1027, (1981).Google Scholar
[9] Reynolds, W.N., Physical Properties of Graphite, Elsevier Pub. Co. LTD., New York, 1968.Google Scholar