MAGNETIC-FIELD EFFECTS ON DYNAMIC BEHAVIOR OF EXCITED MOLECULES IN THE GAS-PHASE

Magnetic quenching is found for the phosphorescence from the R(3)B(2) levels of gaseous CS2 and the fluorescence from the (CB2)-B-1 levels o f gaseous SO2. The magnetic field effect (MFE) of CS2 can be explained by a fast intra-molecular relaxation process due to the Zeeman intera ction and by a collision-induced process characteristic of the small m olecule limit. The MFE of SO2 can be explained by collision-free direc t and indirect mechanisms characteristic of the intermediate case. The relation between the MFE of SO2 and its predissociation is also studi ed. On the other hand, magnetic quenching and enhancement are found fo r the chemiluminescence observed in the reaction of CS2 with O and ass igned to emission of excited SO2 and SO. The quenching can be explaine d by the magnetic quenching of the (CB2)-B-1 levels of SO2. The enhanc ement may be due to excited levels of SO, but its mechanistic study ha s not yet been concluded.