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Laser Induced Raman Spectra of Some Tungstates and Molybdates
R K Khanna1, W S Brower1, B R Guscott1
1Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
Summary
This study analyzes the Raman spectra of calcium tungstate, calcium molybdate, lead tungstate, and lead molybdate crystals. Polarization data helped classify vibrational modes and distinguish between rotational and translational lattice vibrations.
Area of Science:
- Solid-state physics
- Materials science
- Spectroscopy
Background:
- Calcium tungstate (CaWO4), calcium molybdate (CaMoO4), lead tungstate (PbWO4), and lead molybdate (PbMoO4) are scheelite-type crystals with potential applications in various fields.
- Understanding their vibrational properties is crucial for predicting and optimizing their performance.
Purpose of the Study:
- To investigate the Raman spectra of CaWO4, CaMoO4, PbWO4, and PbMoO4 single crystals.
- To classify the observed vibrational modes based on polarization data and crystal symmetry.
- To differentiate between rotational and translational lattice vibrations.
Main Methods:
- Recording Raman spectra using He-Ne (6328 Å) and Argon ion (4880 Å) lasers.
- Analyzing polarization of the scattered light.
- Comparing spectral features across different crystal samples.
Main Results:
- Unambiguous classification of observed fundamental vibrations into Raman active species for the C4h point group.
- Distinction between rotational and translational lattice vibrations based on low-frequency spectral analysis.
- Detailed spectral data for four related tungstate and molybdate crystals.
Conclusions:
- The study successfully characterized the vibrational dynamics of CaWO4, CaMoO4, PbWO4, and PbMoO4 crystals.
- Polarization-resolved Raman spectroscopy is an effective tool for assigning vibrational modes in C4h crystals.
- The findings contribute to a deeper understanding of lattice dynamics in these important materials.
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