  Nearly half a century ago, I joined an ambitious research project aimed at
establishing the mechanism of photodecomposition of ionic salts. We measured
the mobilities and lifetimes of photoelectrons and photoholes in silver bromide
in order to get an early-stage knowledge of the process. The last pairs of
quantities to study were the diffusion coefficients for which we got results,
highly controversial at that time. Now we show that the diffusion data suggest
the formation of itinerant Jahn Teller small polarons as the next-stage
photo-carriers in silver halides.

Materials Science;Other Condensed Matter