Abstract
The fluorescence line narrowing (FLN) of the N1 and N2 lines of pairs of Cr3+ ions in concentrated ruby has been studied. The structure of the narrowed lines has been explained and measurements of the homogeneous width have been improved. By use of the FLN and time-resolved spectroscopy, spectral transfer within the N1 line has been investigated. A two-phonon-assisted process has been found to be responsible for the transfer.