Femtosecond pump-probe measurements of non-radiative relaxation in LiAlO2 : V3+

Wells, J P R and Grinberg, M and Wynne, K and Han, T P J (2006) Femtosecond pump-probe measurements of non-radiative relaxation in LiAlO2 : V3+. Journal of Physics: Condensed Matter, 18 (16). pp. 3967-3974. ISSN 0953-8984

Abstract

We report on time-resolved studies of non-radiative relaxation of V3+ ions in LiAlO2 by means of a two-beam, pump-probe saturation experiment performed with the 150 A pulsed output of a Ti-sapphire laser. Exciting into the vibronically broadened (3)A(2) -> T-3(1) transition at 800 nm, a T-3(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 3A2 ground state have been obtained using Mott's expression, yielding best-fit parameters of W-0 = (5.2 +/- 1) x 10(9) Hz and W-1 = (7.5 +/- 1) x 10(10) Hz for a potential barrier of Enr = 530 +/- 50 cm(-1).

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