EXCITED-STATE PROPERTIES OF 4-BROMOBIPHENYL AND 4,4'-DIBROMOBIPHENYL

The triplet-triplet absorption spectra for 4-bromobiphenyl and 4,4'-di bromobiphenyl have been determined by pulse radiolysis and laser flash photolysis in benzene, cyclohexane, isopropanol, ethanol and methanol . The extinction coefficient for the triplet-triplet absorption of 4-b romobiphenyl and 4,4'-dibromobiphenyl in benzene was calculated to be 32,000 +/- 500 dm3 mol-1 cm-1 and 39,500 +/- 500 dm3 mol-1 cm-1, respe ctively. The quenching of triplet by ground state molecules was not ve ry significant. The energy transfer rate constants from benzene to 4-b romobiphenyl and 4,4'-dibromobiphenyl were found to be diffusion contr olled. The quenching of naphthalene fluorescence by brominated bipheny l was also found to be diffusion controlled.