Relaxation of electronic excitations in beryllium oxide: A time-resolved vacuum-UV spectroscopy study

Beryllium oxide crystals are studied by time-resolved optical and luminesce nce vacuum-UV spectroscopy. The low-temperature luminescence spectra and th e luminescence decay kinetics (2.5-10 eV, 1-500 ns) upon selective photoexc itation, and also the luminescence excitation and reflectivity spectra (8-3 5 eV), are analyzed for BeO crystals with the optic axis aligned parallel a nd perpendicular to the electric vector of exciting polarized synchrotron r adiation. It is found that the radiative relaxation of electronic excitatio ns proceeds through a large number of channels. The excited states of self- trapped excitons are characterized by different multiplicity depending on t he excitation energy and the sample orientation. (C) 2001 MAIK "Nauka/Inter periodica".