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Long‐Wavelength Optical Phonons of AgBr x Cl 1− x Mixed Crystals

1974; Wiley; Volume: 66; Issue: 1 Linguagem: Inglês

10.1002/pssb.2220660118

1521-3951

B. Bootz, W. von der Osten, N. Uhle,

Spectroscopy and Quantum Chemical Studies

Abstract Infrared reflectivity and second‐order Raman scattering in the mixed crystal system AgBr x Cl 1− x , were studied at 77 K. The TO(Γ) and LO(Γ) phonon frequencies obtained by means of a Kramers‐Kronig analysis shift continuously between their energetic positions in the pure components indicating one‐mode behaviour of the system. This result is discussed in view of a recent model that describes the optical modes of a mixed crystal. The LO(Γ) phonon frequencies taken from the Raman spectra are found to be slightly lower. A resonant enhancement of the 2L0 scattering process that occurs for z = 0.42 with shorter‐wavelength excitation is used to determine the longitudinal optical phonon frequency.