Femtosecond pump-probe measurements of non-radiative relaxation in LiAlO(2):V(3+).

We report on time-resolved studies of non-radiative relaxation of V(3+) ions in LiAlO(2) by means of a two-beam, pump-probe saturation experiment performed with the 150 fs pulsed output of a Ti-sapphire laser. Exciting into the vibronically broadened [Formula: see text] transition at 800 nm, a (3)T(1) relaxation time of 199 ps has been measured at 4 K. This value decreases to 82 ps at room temperature, representing a reduction in the lifetime of a factor of 2.5 due to internal-conversion processes. The relative probabilities for non-radiative, phonon-assisted barrier hopping and quantum mechanical tunnelling through the potential barrier to the (3)A(2) ground state have been obtained using Mott's expression, yielding best-fit parameters of W(0) = (5.2 ± 1) × 10(9) Hz and W(1) = (7.5 ± 1) × 10(10) Hz for a potential barrier of E(nr) = 530 ± 50 cm(-1).