Absorción óptica a altas presiones del TLGaSe$_{2}$

Abstract

In this paper the spectrum of optical normal transmission not polarized of TlGaSe$_{2}$ is measured as a function of pressure up to 27.6 GPa at room temperature. Our results show that in the range of the visible exist the contributions of two direct gaps of energy, which present a linear dependence with the pressure. The weak transition E$_{A}(\Gamma _2^v \to \Gamma _{3,1}^c )$ assigned to the fundamental gap of energy, decreases up to 1.5 GPa with a linear coefficient of -5.31$\times$10$^{ - 2}$ eVGPa$^{ - 1}$ and the transition E$_{B}(\Gamma _2^v \to \Gamma _{3,2}^c )$ shows a coefficient of -9.95$\times$10$^{ - 2}$ eVGPa$^{ - 1}$ up to 5.3 GPa (limit of pressure in the visible spectrum). The results in the infrared do not show the presence of the transition E$_{A}$ allowing to see only the behavior of the second transition rightly up to the pressure of metallization 24.6 GPa. In the range of pressure studied from 0.0 to 27.6 GPa, the transition E$_{B}$ shows a not linear behavior with the pressure of quadratic coefficient 1.83$\times$10$^{ - 3}$ eVGPa$^{ - 2}$.