Ultrafast electron transfer dynamics of a Zn(II)porphyrin-viologen complex revisited

S2 vs S1 reactions and survival of excess excitation energy

Jonas Petersson, Mattias Eklund, Jan Davidsson, Leif Hammarström

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

The photoinduced electron transfer reactions in a self-assembled 1:1 complex of zinc(II)tetrasulphonatophenylporphyrin (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 S1 states, respectively. The resulting electron transfer to MV2- occurred, surprisingly, with the same time constant of τFET=180 fs from both electronic states. The subsequent back electron transfer was rapid, and the kinetics was independent of the initially excited state (τBET = 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 ZnTPSS 3-/MV+ spectra suggest that the forward electron transfer from the S2 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 electron transfer rates for the different excited states are also discussed.

Original languageEnglish
Pages (from-to)14329-14338
Number of pages10
JournalJournal of Physical Chemistry B
Volume114
Issue number45
DOIs
Publication statusPublished - Dec 8 2010

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Viologens
Excitation energy
Porphyrins
porphyrins
electron transfer
Excited states
Electrons
excitation
Ground state
energy
ground state
Electronic states
Field effect transistors
Absorption spectroscopy
time constant
S(2) complex
Charge transfer
Zinc
absorption spectroscopy
field effect transistors

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Chemistry
  • Surfaces, Coatings and Films

Cite this

Ultrafast electron transfer dynamics of a Zn(II)porphyrin-viologen complex revisited : S2 vs S1 reactions and survival of excess excitation energy. / Petersson, Jonas; Eklund, Mattias; Davidsson, Jan; Hammarström, Leif.

In: Journal of Physical Chemistry B, Vol. 114, No. 45, 08.12.2010, p. 14329-14338.

Research output: Contribution to journalArticle

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