Electron excitations in LiB3O5 crystals with defects: Low-temperature time-resolved luminescence VUV spectroscopy

The dynamics of electron excitations and luminescence of LiB3O5 (LBO) singl e crystals was studied using low-temperature luminescence vacuum ultraviole t spectroscopy with a subnanosecond time resolution under photoexcitation w ith synchrotron radiation. The kinetics of the photoluminescence (PL) decay , the time-resolved PL emission spectra, and the time-resolved PL excitatio n spectra of LBO were measured at 7 and 290 K, respectively. The PL emissio n bands peaking at 2.7 eV and 3.3 eV were attributed to the radiative trans itions of electronic excitations connected with lattice defects of LBO. The intrinsic PL emission bands at 3.6 and 4.2 eV were associated with the rad iative annihilation of two kinds of self-trapped electron excitations in LB O. The processes responsible for the formation of localized electron excita tions in LBO were discussed and compared with those taking place in wide-ga p oxides. (C) 2001 MAIK "Nauka/Interperiodica".