Summary
Considerations based on the crystal structure of diamond enable its nine eigenvibrations to be arranged on a descending scale of frequency. The magnitude of the force-oonstants involved can also be defined within narrow limits. The numerical values of the frequencies evaluated on the basis of the theoretical formulæ show a close agreement with the observed values. The geometry of the modes determines the changes in bond-polarisabilities and electron distributions produced by them, from which their activities in light-scattering and in infra-red absorption can be ascertained both in the first and in the second approximation. A comparison of the results with the experimental facts shows a striking agreement. The observed intensity of the second-order effects in relation to those of the first order indicates that the eigenvibrations are localised in volume elements comparable in size with the lattice cells of the crystal.
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References
Krishnan, R. S.Proc. Ind. Acad. Sci., A, 1947,26.
—Ibid.,, 1944,19, 216.
—Ibid.,, 1944,19, 298.
—Ibid.,, 1946,24, 25.
—Ibid.,, 1946,24, 45.
Mani, Miss AnnaIbid.,, 1944,19, 231.
Raman, C. V.Ibid.,, 1943,18, 237.
— and Ramaseshan, S.Ibid.,, 1946,24, 1.
Ramanathan, K. G.Ibid.,, 1947,26, 481.
—Ibid.,, 1947,26, 469.
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Raman, C.V. The vibration spectra of crystals. Proc. Indian Acad. Sci. 26, 356 (1947). https://doi.org/10.1007/BF03170893
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DOI: https://doi.org/10.1007/BF03170893