SOLVENT INFLUENCES ON THE SINGLET QUENCHING OF CHLOROPHYLL a BY 2, 5-DIMETHYL-p-BENZOQUINONE |
| |
| Authors: | L V NATARAJAN † JANET E RICKER† ROBERT E BLANKENSHIP RAYMOND CHANG† § |
| |
| Institution: | *Chemistry Department, Amherst College, Amherst, MA 01002, USA.;†Chemistry Department, Williams College, Williamstown, MA 01267, USA |
| |
| Abstract: | Abstract— The quenching of chlorophyll a excited singlet states by 2.5-dimethyl- p -benzoquinone has been investigated in solvents of varying viscosity and polarity. The observed singlet lifetimes showed little variation in several hydrocarbon solvents. Stern-Volmer constant K depends on the viscosity of the solvent, although cyclic and straight-chain hydrocarbons behave somewhat differently. The decrease of the K values with increase of viscosity suggests that the quenching mechanism is at least partly dynamic, although there is evidence for static quenching as well. The influence of solvent polarity on the K values was found to be insignificant, which is consistent with a very short-lived ion pair intermediate formed by electron-transfer quenching. |
| |
| Keywords: | |
|
|
