Ultrafast Electron Transfer Dynamics of a Zn(II)porphyrin-Viologen Complex Revisited S-2 vs S-1 Reactions and Survival of Excess Excitation Energy
2010 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, no 45, 14329-14338 p.Article in journal (Refereed) Published
The photoinduced electron transfer reactions in a self-assembled 1 1 complex of zinc(II)tetrasulphonatophe nylporphyrin (ZnTPPS4-) and methylviologen (MV2+) in aqueous solution were investigated with transient absorption spectroscopy ZnTPPS4- was excited either in the Soret or one of the two Q-bands corresponding to excitation into the S-2 and S-1 states respectively The resulting electron transfer to MV2+ occurred surprisingly with the same time constant of tau(FET) = 180 fs from both electronic states The subsequent back electron transfer was rapid and the kinetics was independent of the initially excited state (tau(BET) = 700 fs) However ground state reactants in a set of vibrationally excited states were observed The amount of vibrationally excited ground states detected increased with increasing energy of the initial excited state showing that excess excitation energy survived a two-step electron transfer reaction in solution Differences in the ZnTPSS3-/MV+. spectra suggest that the forward election transfer from the S-2 state at least partially produces an electronically excited charge transfer state which effectively suppresses the influence of the inverted regime Other possible reasons for the similar election transfer rates for the different excited states are also discussed
Place, publisher, year, edition, pages
2010. Vol. 114, no 45, 14329-14338 p.
IdentifiersURN: urn:nbn:se:uu:diva-139266DOI: 10.1021/jp9116867ISI: 000284018000026OAI: oai:DiVA.org:uu-139266DiVA: diva2:380924