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A fluorescence of alkali halide single crystals doped with the corresponding alkali hydroxide has been observed and is attribut('d to the A '};+-'X'll emission of a photoproduced hydroxyl radical. A phosphorescence of systems containing the hydroxide ion has also been noted at >,,,,400 mp and is attributed to a 4};--.X'll emission of the OH radical. Photoprocesses in systems containing the OH-ion, as well as in aqueous systems containing·certain salts and acids,· are discussed in a qualitative way.

Phosphorescence lifetimes of benzene and methylbenzene derivatives, deuterated and undeuterated, have been measured in glassy matrices at 4.2 and nOK. Spin-orbit coupling calculations have been performed for benzene (D6h), distorted benzene (Du), and toluene; these calculations included spin-own-orbit, spinother-orbit, and vibronic considerations and were extended to all the methylbenzenes by a vector-sum semiempirical method. Franck-Condon calculations wete performed for all methylated, deuterated, and distorted benzene derivatives. The results of these calculations lead to a general understanding of phosphorescence lifetimes, at least insofar as these are affected by either methylation or deuteration or both. Matrix effects and temperature effects on the phosphorescence lifetimes are largest in the case of benzene and toluene and decrease with increasing methylation of benzene and with increasing size of the polynuclear hydrocarbon. We attribute this sensitivity to the small size of the space available to the '/I" subsystem in benzene, to the forbiddenness of the electric-dipole Tl-+So process in this system, and to the ease with which matrix effects may perturb the rather "naked" skeleton of this molecule and its less-methylated derivatives. A concept of solvent-assisted distortions is introduced in order to explain the direction of solvent and temperature effects and the means whereby these effects become operative. This last is a very tenuous suggestion, its primary merit being that it provides some rationalization of the observed phenomenology.

Nitrite salts of the post-transition-series metals exhibit a long-lived luminescence centered at ∼5500 Å. This emission is characteristic of both the solid state and frozen glassy solutions. It is suggested that this emission originates in a triplet state (T1) of the system, and that, in fact, it is a phosphorescence of T1→S0 molecular type connecting with the ground singlet state (S0). It is shown that the spin–orbit coupling responsible for the enhanced intersystem crossing is introduced by the metal counterion and that such introduction is also dependent on the presence of nitrite-counterion covalency. The increased spin–orbit coupling is manifested in the following ways: (i) a decrease in the phosphorescence lifetime, τp, (ii) an increase in the relative quantum yield ratio Φp / Φf of phosphorescence to fluorescence, (iii) an increase in the T1←S0 absorptivity—which absorptivity is responsible for the yellow-orange colors of the heavy-metal nitrites.