Raman spectroscopy study of the Fermi resonance between a local vibration and the two‑phonon spectrum in PbI2 crystal
Abstract
The problem of complex Fermi resonance (FR) involving a local vibration is considered. It is shown for the first time that in the PbI2 crystal, owing to the features of phonon bands, the following two effects superpose on each other: (1) the traditional FR between the fundamental Ω(A1g) vibration and the two‑phonon states (TPS) arising from the 2Ω(Eu) vibrations, and (2) the FR between the impurity vibration and the same TPS band. It is shown theoretically that in the case of such complex FR the shape of the spectrum strongly depends on the impurity concentration, anharmonic constants and the phonon band structure. An analysis of experimental data and comparison with theory is made. Copyright
- Publication:
-
Journal of Raman Spectroscopy
- Pub Date:
- March 2008
- DOI:
- 10.1002/jrs.1826
- Bibcode:
- 2008JRSp...39..363Y