LASER RAMAN SCATTERING STUDIES OF CRYSTALS
Semiannual progress rept. 16 Dec 1966-15 Jun 1967
JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF PHYSICS
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Temperature dependent Raman spectroscopy of quartz has revealed the existence of a new optical lattice vibration mode which appears to play a fundamental role in the alpha-beta phase transition. Continued temperature dependent Raman measurements of Strontium Titanate have also disclosed a new moving component in the spectrum. Additional measurements have also shown that the three sharp Raman lines which are present at all temperatures below the 110 degrees K cubic to tetragonal transition probably arise from local breaking of the translational symmetry by inhomogeneous strain within the domain walls. Intensity vs. temperature measurements of the strong component at 78 reciprocal cm room temperature value have failed to confirm our earlier conclusion that part of the room temperature Raman spectrum of Strontium Titanate is of first order. Preliminary Raman measurements have been performed on KDP, and have failed to produce conclusive evidence for an anticipated soft mode which was predicted by Cochran.
- Lasers and Masers
- Atomic and Molecular Physics and Spectroscopy