Excited-state absorption in the Cr6+O2- center in Li2B4O7 glass

Abstract

We present excited state absorption (ESA) measurements of the Cr:Li2B4O7 glass along with preliminary interpretation. The most distinct feature in the ESA characteristics is connected with the presence of chromium in its hexe-valence states. The Cr6+ ions appear to contribute in the deexcitation processes and their evidence can be seen in the ESA spectra under excitation wavelength at 308 nm. We interpret the ESA spectra detected with UV excitation in terms of transitions in the framework of Cr5+O- center which forms aster charge- transfer-type absorption in (CrO4)2- group. We assume the presence of the double-electron state of the 3d22p4 electronic configuration together with crystal field-split states of the 3d12p5 configuration, both allow to reproduce the obtained ESA spectra.