PHOTOLUMINESCENCE STUDIES ON RUBY AT 4.2 K

Abstract

We have made the PL measurements on ruby at room temperature and 4.2 K. The characteristic R1 and R2 lines of chromium in ruby are found to be absent in the spectra recorded at 4.2 K. Instead of these characteristic lines a band centered on 1.6 eV is observed. A possible explanation has been discussed in terms of co-existence of the two electronic states due to presence of Cr3+ and Cr4+ ions in the ruby lattice.