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Optical Relaxation Processes in Polymers at Low Temperatures

  • Dietrich Haarer
Part of the Advances in Cryogenic Engineering book series (ACRE, volume 30)

Abstract

The investigation of microscopic parameters of amorphous materials with the means of optical spectroscopy is rather difficult, the main difficulty being the poor optical resolution due to inhomogeneous broadening effects. The nature of the inhomogeneous broadening is rather well understood on a qualitative level. In a typical experiment, one dopes an amorphous polymeric material with molecules absorbing in the electronic bandgap of the polymer host material. The individual molecules will then occupy different ‘sites’; in each site their microscopic environment will be somewhat different. This is symbolically depicted in Fig. 1 for three identical molecules occupying three different sites. Due to ‘crystal field effects’ the absorption energy of the three sites will differ; the molecules will absorb at the frequencies ωl, ω2 and ω3 respectively, as is symbolically depicted in Fig. 1. The frequency spread and, hence, the inhomogeneous bandwidth is a measure of both, the molecule-matrix interaction and the degree of disorder. High quality single crystals are characterized by extremely small inhomogeneous broadening (0.1 – 1 cm−1), amorphous materials show large inhomogeneous broadening effects (100 – 1000 cm−1).

Keywords

High Energy Side High Quality Single Crystal Crystal Field Effect Homogeneous Linewidth Ground State Depletion 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    N. Bloembergen, E. M. Purcell and R. V. Pound, Phys.Rev. 73: 679 (1948)CrossRefGoogle Scholar
  2. 2.
    A. Szabo, Phys.Rev. B 11: 4512 (1975)CrossRefGoogle Scholar
  3. 3.
    B. M. Kharlamov, R. I. Personov and L. A. Dykovskaya, Opt.Commun. 12: 191 (1974)CrossRefGoogle Scholar
  4. 4.
    A. A. Gorokhovskii, R. K. Kaarli and L. A. Rebane, JETP Letters 20: 216 (1974)Google Scholar
  5. 5.
    G. J. Small in: “Molecular Spectrscopy”, V. M. Agranovich and R. M. Hochstrasser, ed., North-Holland Publ., New York (1983)Google Scholar
  6. 6.
    J. Friedrich, J. D. Swalen and D. Haarer, J.Chem.Phys. 73: 705 (1980)CrossRefGoogle Scholar
  7. 7.
    S. Voelker and J. H. van der Waals, Mol.Phys. 32: 1703 (1976)CrossRefGoogle Scholar
  8. 8.
    A. Abragam, “The principles of nuclear magnetism”, Clarendon Press, Oxford (1961)Google Scholar
  9. 9.
    S. Voelker, R. M. Macfarlane, A. Z. Genack, H. P. Trommsdorff and J. H. van der Waals, J.Chem.Phys. 67: 1959 (1977)CrossRefGoogle Scholar
  10. 10.
    A. A. Gorokhovskii and L. A. Rebane, Opt.Commun. 20: 144 (1977)CrossRefGoogle Scholar
  11. 11.
    J. M. Hayes, R. P. Stout and G. J. Small, J.Chem.Phys. 74: 4266 (1981)CrossRefGoogle Scholar
  12. 12.
    H. P. H. Thijssen, A. I. M. Dicker and S. Voelker, Chem.Phys.Lett. 92: 7 (1982)CrossRefGoogle Scholar
  13. 13.
    J. Hegarty and W. M. Yen, Phys.Rev.Lett 43: 1126 (1979)CrossRefGoogle Scholar
  14. 14.
    J. Friedrich, H. Wolfrum and D. Haarer, J.Chem.Phys. 77: 2309 (1982)CrossRefGoogle Scholar
  15. 15.
    R. Jankowiak and H. Bässler, Chem.Phys.Lett. 95: 310 (1983)CrossRefGoogle Scholar
  16. 16.
    S. K. Lyo and R. Orbach, Phys.Rev. B 22: 4223 (1980)CrossRefGoogle Scholar
  17. 17.
    S. K. Lyo, Phys.Rev.Lett. 48: 688 (1982)CrossRefGoogle Scholar
  18. 18.
    P. Reineker and H. Morawitz, Chem.Phys.Lett. 86: 359 (1982)CrossRefGoogle Scholar
  19. 19.
    P. Reineker and H. Morawitz, Solid State Comm. 42: 609 (1982)CrossRefGoogle Scholar
  20. 20.
    S. K. Lyo in: “Electronic Excitations and Interaction Processes in Organic Molecular Aggregates”, P. Reineker, H. Haken and H. C. Wolf, eds., Springer Series in Solid State Sciences (1983)Google Scholar
  21. 21.
    A. Gutierrez, G. Castro, G. Schulte and D. Haarer in: “Electronic Excitations and Interaction Processes in Organic Molecular Aggregates”, P. Reineker, H. Haken and H. C. Wolf, eds., Springer Series in Solid State Sciences (1983)Google Scholar

Copyright information

© Springer Science+Business Media New York 1984

Authors and Affiliations

  • Dietrich Haarer
    • 1
  1. 1.Physikalisches InstitutUniversität BayreuthGermany

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