Absorption and emission spectroscopic characterisation of F3 colour centers in a LiF crystal

For a LiF crystal containing F3 (R1, R2), F2, F3 , F4 (N1, N2), F3 , and F2 colour centers the absorption and emission spectroscopic behaviour of the F3 centers is studied. The absorption cross-section spectrum and the number density of F3 centers are extracted from saturable absorption and transmission measurements. Additionally fluorescence quantum distribution measurements and fluorescence lifetime measurements are carried out to determine the stimulated emission cross-section spectrum and the fluorescence quantum yield of the F3 centers. Fluorescence excitation spectroscopy reveals the presence of an absorption band with its absorption peak around 700 nm (called R 1 band) in addition to the ground-state to first excited-state F3 center absorption band centered at 800 nm (called R 2).