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HL: Fachverband Halbleiterphysik
HL 43: Optical Properties II
HL 43.8: Vortrag
Donnerstag, 21. März 2024, 11:30–11:45, EW 561
Phonon-phonon interactions in the polarization dependence of Raman scattering — •Nimrod Benshalom1, Noam Pinsk1, Maor Asher1, Olle Hellman2, and Omer Yaffe1 — 1Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel — 2Department of Molecular Chemistry and Material Science, Weizmann Institute of Science, Rehovot 76100, Israel
Inelastic light scattering offers an experimentally robust and accessible method to probe the potential surface governing ionic motion in crystals. Its analysis, however, usually relies on harmonic theory that predicts Lorentzian line shapes, monotonic temperature trends and strict selection rules. Since the spectra of dynamically disordered crystals can violate all of these, new evaluation schemes are required to realize the potential for physical insight dormant in light scattering experiments.
We have found that the polarization dependence of Raman scattering in organic crystals at finite temperatures can only be described by a fourth-rank tensor formalism. This generalization of the second-rank Raman tensor stems from the effect of off-diagonal components in the crystal self-energy on the light scattering mechanism. We thus establish a novel manifestation of phonon-phonon interaction in inelastic light scattering, markedly separate from the better-known phonon lifetime.
Keywords: Light scattering; Structural dynamics; Anharmonicity; Self-energy