Simultaneous generation of different types of ion pairs upon charge-transfer excitation of a donor - acceptor complex revealed by ultrafast transient absorption spectroscopy

Omar Abdelsaboor, Eric Vauthey*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

The excited-state dynamics of the methylperylene/tetracyanoethylene (MPe/TCNE) donor-acceptor complex has been investigated in various solvents using femtosecond transient absorption spectroscopy. The transient spectra reveal the formation of two types of ion pairs: The first (IP1), constituting the major fraction of the total ion-pair population, is characterized by a broad and red-shifted absorption spectrum compared to that of the free MPe cation and by a subpicosecond lifetime, whereas the second (IP2) has a spectrum closer to that of MPe cation and a lifetime of a few picoseconds. A substantial polarization anisotropy was observed with IP1 but not with IP2, indicating a relatively well-defined structure for the former. The reaction scheme that best accounts for the observed dynamics and its solvent dependence involves the simultaneous excitation of complexes that differ by their electronic coupling. The more coupled complexes have a high absorption coefficient and thus yield IP1, which undergoes ultrafast charge recombination, whereas the less coupled complexes have a lower probability to be excited and lead to the longer-lived IP2.

Original languageEnglish (US)
Pages (from-to)5804-5809
Number of pages6
JournalJournal of Physical Chemistry A
Volume112
Issue number26
DOIs
StatePublished - Jul 3 2008

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Fingerprint Dive into the research topics of 'Simultaneous generation of different types of ion pairs upon charge-transfer excitation of a donor - acceptor complex revealed by ultrafast transient absorption spectroscopy'. Together they form a unique fingerprint.

Cite this