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Extended x-ray-absorption fine-structure Debye-Waller factors and vibrational density of states in amorphous arsenic

1987; American Physical Society; Volume: 35; Issue: 3 Linguagem: Inglês

10.1103/physrevb.35.1236

1095-3795

Pier Paοlο Lottici,

High-pressure geophysics and materials

A connection between Raman intensities and the extended x-ray-absorption fine-structure (EXAFS) nearest-neighbor mean-square relative displacement ${\ensuremath{\sigma}}_{R}^{2}$, stressing the predominance of bond-compression mechanisms in depolarized Raman scattering, is tested in amorphous arsenic. Parameter-free relative densities of states, which enter ${\ensuremath{\sigma}}_{R}^{2}$ calculations, are obtained from the reduced Raman intensity and from neutron inelastic scattering data, in the framework of a nearest-neighbor central-force model. In both cases, the experimental temperature dependence of the EXAFS Debye-Waller thermal disorder parameter is well reproduced. The results are discussed in terms of Einstein and Debye models through a calculation of the negative moments of the relative density of states.