ROTATIONAL STATE DEPENDENCE OF EXTERNAL MAGNETIC-FIELD EFFECTS ON YIELD AND DECAY OF FLUORESCENCE OF S-TRIAZINE VAPOR

Effects of external magnetic field (H) on intensity and decay of fluorescence of s-triazine vapor have been examined under collision-free conditions following excitation at the individual rotational lines belonging to the 601 or 602 absorption band of the S0→S1 transition. The fluorescence intensity is reduced by H and the value of the fluorescence lifetime is increased by H, as far as the slowly decaying portion is concerned. The efficiency of the magnetic quenching of fluorescence depends not only on the vibrational level, but also on the rotational level excited and a good correlation in rotational state dependence between the fluorescence lifetime at zero field and the efficiency of the magnetic quenching of fluorescence is found at 602. As J′ of the excited level increases, the lifetime of the slow fluorescence increases, while the magnetic quenching becomes more effective. It is shown that both external magnetic field and molecular rotation play a role to increase the level density of the triplet state coupled to S1. © 1990 American Institute of Physics.