Dynamical processes in excited states of Cr 3+ probed by the Raman effect

Abstract

By exposing single crystals of chromium doped α Al 2O 3, Y 3Al 5O 12, ZnAl 2O 4 and Be 3Al 2(SiO 3) 6 to 1 W of radiation of an cw argon-ion laser operating at λ = 514.5 nm, part of this radiation is absorbed and population takes place of the component levels of 2E which are - for these solids - between 14410 cm −1 and 14720 cm −1 above the ground state of Cr 3+. That part of the laser radiation not absorbed by the sample is sufficiently intense to excite electronic Raman transition between the component levels of 2E. Inhomogeneous and homogeneous broadening processes are responsible for the width of emission lines and the effect of these processes reveal themselves quite clearly if the temperature dependent line width of the electronic Raman transition is compared to that of the phosphorescence transitions which connect the levels of 2E with the ground state. Of the two processes, the homogeneous broadening process is of interest here because its dynamical aspects can be probed using the electronic Raman process as a tool.