Strong luminescence and enhanced stimulated emission in CuCl microcrystalline films

We have developed a method for obtaining microcrystalline films of metal halides. It is based on shot-like IR laser irradiation of the films with CO2 laser (wavelength, 10.6 μm; power, 10W), with the substrate kept in contact to a 77K copper block. Microcrystalline CuCl films prepared in this method shows strongly enhanced free exciton luminescence. Under intense excitation of the films, stimulated emission due to recombination of excitonic molecules is observed. The threshold excitation intensity for the stimulated emission is about 100 kW/cm2, which is by an order of magnitude smaller than that reported for CuCl microcrystals embedded in NaCl crystal matrixes