Time-resolved spectroscopy of the level-anticrossing effect in exciton emission

The paper reports a time-resolved study of the Zeeman (spin) sublevel anticrossing effect in triplet bound-exciton emission in GaSe crystals. The shape of the anticrossing signal was found to vary substantially during the excited-state lifetime. One observes, in particular, a splitting of the Lorentzian-shaped peak of the signal into two peaks, with their separation increasing with time. A theoretical description of the effect is proposed, which permits explanation of the nature of the observed changes and determination of the lifetime of the interacting states.