Excited state absorption in chromium doped Li2B4O7 glass

Excited state absorption (ESA) measurements of the CT:Li2B4O7 glass (Cr:LBO -glass) along with preliminary interpretation are presented. The presence o f chromium in its tri- (d(3)) and hexa- (d(0)) valence states is observed, Both Cr3+ and Cr6+ ions appear to contribute in the de-excitation processes and can be attributed in the ESA spectra under excitation wavelengths at 3 08 nm, 488 nm, 515 nm and 610 nm. The ESA spectra detected with W excitatio n have been interpreted in terms of transitions in the framework of the Cr5 +O-centre, which forms after charge-transfer-type absorption in the [CrO4]( 2-) group. Assumption of the double-electron state of the 3d(2)2p(4) electr onic configuration together with crystal-field-split states of the 3d(1)2p( 5) configuration allowed us to reproduce the obtained ESA spectra. The ESA spectra of the Cr3+ ions have different characteristics and are related to transitions to the conduction band.