Anomalous pressure behavior of ZnSe Raman spectrum

Autor:	R. Lauck, Peihong Zhang, Manuel Cardona, R. E. Tallman, G.P. Lindberg, B. A. Weinstein, B. Shih
Rok vydání:	2009
Předmět:	Pressure range Phase transition symbols.namesake Condensed matter physics Chemistry Lattice (order) Anharmonicity Density of states symbols Condensed Matter Physics Raman spectroscopy Molecular physics
Zdroj:	High Pressure Research. 29:476-481
ISSN:	1477-2299 0895-7959
DOI:	10.1080/08957950903339937
Popis:	The effects of pressure on the 1- and 2-phonon Raman spectrum of 68Zn76Se are investigated at 295, 125, and 11 K. At 295 K, the TO(Γ) line-width exhibits an anomalous 10-fold broadening in the pressure range 10.5–13 GPa, prior to the B1 phase transition. Other spectral features remain reasonably sharp. At 125 and 11 K the TO(Γ) anomaly is not seen. After the phase transition, a broadband is also seen in the TO(Γ) region for a wide range of downstroke pressures. Two explanations are considered: strong anharmonic coupling between TO(Γ) and (TO2–TA1)(X,K) difference modes, and structure or local bonding changes within the ZnSe lattice. First principles calculations of the 1- and 2-phonon density of states as a function of pressure are carried out and used to test the effect of the TO(Γ)→(TO 2–TA 1)(X,K) decay process. The results cannot rule out contributions from additional anharmonic channels and/or structural disorder effects.
Databáze:	OpenAIRE
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