Author(s)

Katharina Hunger, Karl Kleinermanns

Institute for Physical Chemistry, Heinrich-Heine-University, Düsseldorf, Germany.

The fluorescence kinetics of 1,6-diphenyl-1,3,5-hexatriene (DPH) dissolved in cyclohexane was investigated as a function of temperature, concentration and 355 nm excitation pulse energy. At concentrations above 2.5 μM and excitation energies above 1 mJ a long-lived, very intense emission, which appears within less than 5 ns and lasts up to 70 ns, is observed. During the first 50 ns the decay does not follow an exponential but rather a linear behaviour. In oxygen saturated solutions the long-lived emission is suppressed and solely short-lived fluorescence with τ < 5 ns can be detected. A kinetic simulation was performed, based on a model whereupon the long-lived emission originates from the S₁-state and competes with the formation of DPH-O₂ contact charge-transfer complexes and intersystem crossing which both quench the fluorescence. Our investigations show that even the small amount of oxygen dissolved in nitrogen saturated solutions has a distinct influence on the fluorescence kinetics of DPH.

DPH; Time-Resolved; Fluorescence; Simulations; Kinetics; Diphenylpolyenes

K. Hunger and K. Kleinermanns, "Intense Long-Lived Fluorescence of 1,6-Diphenyl-1,3,5-Hexatriene: Emission from the S₁-State Competes with Formation of O₂ Contact Charge Transfer Complex," Open Journal of Physical Chemistry, Vol. 3 No. 1, 2013, pp. 59-67. doi: 10.4236/ojpc.2013.31008.