Abstract
Partially polarized luminescence ( T 1u → A 1 g is observed when excitation is made by linearly polarized light belonging to the A absorption band ( A 1 g → T 1u) of the metal impurity ions with s 2 electron configurations (Ga +, In +, T1 +, Sn 2+ and Pb 2+ in KBr crystals. The degree of polarization at the low energy tail of the A band is larger than that at the high energy tail, i.e. it varies with the photon energy of exciting light. The azimuthal dependence in the (100) plane becomes zero in the [011] direction. The polarization tends to disappear at high temperatures. Arguments are given which make it seem likely that the observed polarization is due to the splitting of the degenerate excited state caused by non-totally-symmetric vibrations around the centre, in other words, due to the dynamical Jahn—Teller effect. The processes in which the polarization is partially transferred from exciting light to emitted light are qualitatively discussed on the basis of the adiabatic potential energy surface of the T 1u excited electronic state in the six dimensional ( A 1 g , E g , and T 2 g configuration coordinate space. The importance of the Jahn-Teller effect is also discussed in connection with the two emission bands excitable in the A absorption.
Published Version
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