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Salt Effect in Ion-Pair Dynamics after Bimolecular Photoinduced Electron Transfer in a Room-Temperature Ionic Liquid.
Journal article

Salt Effect in Ion-Pair Dynamics after Bimolecular Photoinduced Electron Transfer in a Room-Temperature Ionic Liquid.

  • Rosspeintner A Department of Physical Chemistry , University of Geneva , 30 quai Ernest-Ansermet , CH-1211 Geneva , Switzerland.
  • Koch M Department of Physical Chemistry , University of Geneva , 30 quai Ernest-Ansermet , CH-1211 Geneva , Switzerland.
  • Angulo G Institute of Physical Chemistry , Polish Academy of Sciences , 01-224 Warsaw , Poland.
  • Vauthey E Department of Physical Chemistry , University of Geneva , 30 quai Ernest-Ansermet , CH-1211 Geneva , Switzerland.
  • 2018-11-29
Published in:
  • The journal of physical chemistry letters. - 2018
General Materials Science
English Bimolecular photoinduced electron transfer between perylene and two quenchers was investigated in an imidazolium room-temperature ionic liquid (RTIL) and in a dipolar solvent mixture of the same viscosity using transient absorption on the subpicosecond to submicrosecond time scales. Whereas charge separation dynamics were similar in both solvents, significant differences were observed in the temporal evolution of the ensuing radical ions: although small, the free-ion yield is significantly larger in the RTIL, and recombination of the ion pair to the triplet state of perylene is more efficient in the dipolar solvent. The temporal evolution of reactant, ion, and triplet state populations could be well reproduced using unified encounter theory. This analysis reveals that the observed differences can be explained by the strong screening of the Coulomb potential in the ion pair by the ionic solvent. In essence, RTILs favor free ions compared to highly dipolar solvents of the same viscosity.
Language
  • English
Open access status
closed
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https://sonar.ch/global/documents/252807
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