Time dependence of the Hanle effect in the emission of triplet bound excitons in gallium selenide

The dynamics of the magnetic-field-induced depolarization of the circularly polarized radiation of spin-oriented triplet bound excitons in uniaxial crystals has been studied by time-resolved spectroscopy on an example of GaSe. The depolarization of radiation (the Hanle effect) is due to the difference between the behaviors of its sigma(+) and sigma(-) components in a magnetic field. It has been found that the magnetic-field dependences of the sigma(+) and sigma(-) component intensities vary considerably within the lifetime t of the excited states. The form of the magnetic-field dependence of the degree of polarization of the exciton radiation remains generally the same for various t values. A theoretical description of these effects has been proposed.