Collisional Transfer between and Quenching of the 3p3P and 5P States of the Oxygen Atom

The present experimental study was undertaken to investigate collisional excitation transfer from the oxygen 3p3P to 5P states in a controlled low pressure environment. Previous studies of collisional processes involving the 3P state have centered on the measurement of total quenching rate constants with closed-shell collisional partners, such as the inert gases, nitrogen molecules, etc. Simple theoretical considerations suggest that open shell free radical species will be more effective in inducing spin-changing excitation transfer to the 5P state. Approach of an open-shell perturber species in a state of, say, doublet spin multiplicity to an oxygen atom in the 3p3P state will yield both doublet and quartet molecular curves, while approach to the 5P state yields quartet and sextet states. Crossing of quartet curves originating from the 3P and 5P asymptotes will provide a spin-allowed mechanism for collision-induced transitions between the 3P and 5P states, which is not possible with closed-shell partners. This argument ignores the possible importance of excitations in the collision partner. Reprints.