BENZENE-PHOTOSENSITIZED PHOSPHORESCENCE EMISSION FROM BIACETYL . COMPETITIVE QUENCHING BY PI-BONDED MOLECULES

The relative rates of the triplet energy transfer from benzene to monoolefms, nonconjugated diolefins, conjugated diolefins, biacetyl, and 4-pentenal have been measured by the monitoring method using the benzene-photosensitized phosphorescence emission from the triplet biacetyl. The relative energy transfer rates measured by this BPPE method confirm the previously measured rates obtained by the cis-trans isomerization method. It was necessary to measure the quenching effect on the direct phosphorescence emission from the triplet biacetyl (DPE), as quenching of the DPE complicates the kinetics of the BPPE. It is suggested that the cis-trans isomerization method is more reliable in many cases than the BPPE method.