Vibrational progressions due to radiative decay of A1P(v' = 0,2,3,5,6,8) e3S(v' = 3,5,12), a'3S(v' = 11,14),d3D(v' = 5) to the ground state and of e3S(v' = 3,7,9,11,12), d3D(v' = 3,7,11) to the a3P state were obsd. for selective excitation of A1P(v' = 0, ..., 8). The intersystem crossing rate consts., the bottle necks, pathways and rate consts. for internal conversion in the triplet levels and the triplet-singlet radiative rate consts. are explained by an intramol. mixing of electronic states and electron-phonon coupling with the matrix. [on SciFinder (R)]