Depolarisation dynamics of hot luminescence in F centres: the time-resolved spectrum under pulse excitation

Abstract

A theory for the time-resolved secondary radiation from the F centre excited by a photon pulse is formulated on the basis of a vibronic model. It includes the ls ground state and 2s and 2p excited states with a pseudo-Jahn-Teller-type electron-phonon interaction. The transient behaviour of the intensity and polarisation of the radiated photon is calculated as a function of the time interval between the excitation and the detection. It is found that this transient behaviour enables one to distinguish the hot luminescence from the ordinary luminescence more clearly than previously. In particular, the depolarisation due to hot luminescence becomes more prominent in the transient polarisation spectrum than in the case of stationary excitation, where the hot luminescence is usually masked by the tail part of the predominant ordinary luminescence.