Phonon Dynamics in Alexandrite and Ruby.
Abstract
We have measured the resonant phonon relaxation time, tau, as a function of the excited state concentration, N*, and the spot radius, R, for the Cr^{3+}-doped crystals alexandrite and ruby. In addition we have determined tau as a function of the temperature and the magnetic field for ruby at high N*. We find from our analysis of the experimental results that the phonon dynamics is dominated by a combination of spatial and spectral diffusion. The Pair State model was developed to explain these results in more detail. Unlike previous spectral diffusion models, the Pair State model explains the temperature dependence of the relaxation time in a magnetic field. These experiments verified the importance of the A_ {+/- 1/2} ground state level in spectral diffusion, which was not accounted for by previous models. The Pair State model significantly expands the treatment of spectral and spatial diffusion in ruby. Unlike the previous models, it explains the experimental results for both low and high N*. It fits the experimental data for two very different crystals, with reasonable adjustments, and it provides a more detailed picture of the processes which cause spectral diffusion.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 1987
- Bibcode:
- 1987PhDT.......178M
- Keywords:
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- Physics: Condensed Matter