Photophysics of small α-dicarbonyls

Abstract

The triplet kinetics of glyoxal-h ₂ and -d ₂ neat crystals have been studied by the method of microwave-saturation recovery and microwave-induced delayed phosphorescence. In all cases studied the spin level closely associated with the carbonyl direction is the most radiative. The populating rates, however, show a rich diversity among the various x-traps. This is interpreted by having minute distortions of the trap-molecules out of planarity. A large spin-dependence on the deuterium effect of non-radiative decay is reported and an explanation is suggested. A resolved proton hyperfine structure is observed for glyoxal-h ₂ at zero field. Preliminary results on zero-field proton ENDOR are presented.