Photoinduced Crystallization of Amorphous Ice Films on Graphite

We have experimentally discovered a new nonthermal mechanism by which submonolayer and multilayer amorphous ice films, deposited at $T<\mathrm{}100\mathrm{}\mathrm{K}$, crystallize due to UV radiation; the proposed mechanism is that photoexcited charge carriers in the graphite substrate tunnel into defect states in the amorphous film, and induce exothermic relaxation from the metastable amorphous to the stable crystalline phase.