Dephasing times of the vibrons in α- and in α- mixed crystals
- 1 October 1990
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 42 (10) , 5953-5958
- https://doi.org/10.1103/physrevb.42.5953
Abstract
Picosecond time-resolved coherent anti-Stokes Raman spectroscopy measurements were performed on the vibrons in single crystals of α- and on mixed crystals of α- with 0≤x≤0.086. The observed dephasing of the vibrons in pure α- crystals is faster than exponential, and this is well described by adding a Gaussian factor. The Gaussian decay component is assigned to inhomogeneous broadening and could be observed as a result of the high time resolution of our setup. This indicates that the approximations often employed in the case of weak disorder are not applicable in the short-time region of the decay. The exponential dephasing is ascribed to scattering from anharmonic librons and low-frequency phonons. The - factor group splitting and its temperature dependence were determined through analysis of the beating pattern on the spectra, with an accuracy up to 0.007 . In the isotopically mixed crystals, it is shown that the molecules do not act as trapping center for the vibrons. The homogenous dephasing time for the molecules is surprisingly short compared to the decay.
Keywords
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