SPATIAL-DISTRIBUTION OF THE WAVE-FUNCTION OF THE SELF-TRAPPED EXCITONIN AGCL

The results are presented of a high-frequency electron nuclear double resonance (ENDOR) study of the lowest triplet state of the self-trappe d exciton in AgCl. Direct information about the spatial distribution o f the wave function is obtained, which confirms that the exciton in it s triplet state is built up from a strongly localized self-trapped hol e and a very diffuse electron. The electron is mainly contained in a h ydrogenlike 1s orbital with a Bohr radius of 15.1+/-0.6 Angstrom, but near its center the electron density deviates from spherical symmetry and reflects the D-4h charge distribution of the hole. From a comparis on with the results of an ENDOR study of the self-trapped hole, it is concluded that the microscopic and electronic structure of a self-trap ped hole is not significantly altered by the attraction of a shallow e lectron. No evidence is obtained for the formation of Frenkel pairs in AgCl upon ultraviolet irradiation at low temperatures.