PHOTOLYSIS OF NA- - PHOTOBLEACHING OF ABSORBENCY AND QUENCHING OF FLUORESCENCE((CRYPTAND[2.2.2])NA)

The optical properties of the alkalide Na+(cryptand[2.2.2])Na+ are sen sitive to the presence of defect electrons and can be dramatically alt ered by irradiation with light. Fluorescence intensities decrease mark edly at excitation power densities above about 1 mW cm(-2), even thoug h this power level is some 10(7) times lower than that required to aff ect the absorbance. Partial recovery occurs in powder samples over a p eriod of several minutes at 30-100 K. The enhanced quenching of fluore scence is attributed to the presence of photoproduced trapped electron s. Pronounced changes occur in the optical absorbance spectra of vapor -deposited thin films of Na+(cryptand[2.2.2])Na- following irradiation by high intensity doubled- and tripled-YAG laser pulses. The effects are attributed to the intermediate formation of a ''p-band metal'' in which half of the electrons in the ground s(2) state of Na- are Promot ed to the p-level, resulting in a high concentration of electrons trap ped at some distance from the parent anion site.