Analysis of vibronic transitions in titanium doped sapphire using the temperature of the fluorescence spectra

Abstract

An analysis of the fluorescence spectra of titanium doped sapphire crystals for temperatures ranging from 13 to 578 K is made. Zero- and multiphonon assisted electronic transitions are observed at temperatures below 125 K. Zero-phonon transition energies agree with previously reported measured and predicted values. Phonon assisted transitions suggest that two principle modes of lattice vibrations with energies of 220 and 260 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> are coupled to the electronic <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_{2g}</tex> state. A single phonon energy of 173 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> is observed to couple to the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> E <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> electronic state. Crossover energy is estimated to be about 11 800 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> using a simple harmonic approximation. Lineshape analysis is performed. The fluorescence lifetime was measured to be a constant 3.9 μS below 150 K decreasing to 2.9 μs at 300 K.