Optically detected electron paramagnetic resonance studies were made of Zn-vacancy plus Zn-interstitial Frenkel pairs which were produced by 2.5MeV electron irradiation at 4.2K. These revealed transformations, between pairs with differing separations, that were induced by optical excitation at cryogenic temperatures. The interstitial was identified as being the mobile constituent by directly observing its conversion between Td sites which were surrounded by four Se atoms and those which were surrounded by four Zn atoms. The interstitials were therefore caught in the act of performing a single recombination-enhanced diffusion half jump. This uniquely revealed the exact path which was taken during the one-jump diffusion process.

K.H.Chow, G.D.Watkins: Physical Review Letters, 1998, 81[10], 2084-7