Investigation of the Excited-State Dynamics of Radical Ions in the Condensed Phase Using the Picosecond Transient Grating Technique
Received: June 25, 1997 In Final Form: August 26, 1997 Abstract: A study of the dynamics of ground-state recovery of the perylene
radical cation (Pe Download the full text:
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+), of perylene
radical
anion (Pe-), and of anthraquinone radical
anion (AQ-) is reported. In boric
acid glass, the excited-state
lifetime of Pe+ is 35 ± 3 ps, while in
concentrated sulfuric acid, it is smaller than 15 ps, the time
resolution
of the experimental setup. The excited-state lifetime of
Pe+, Pe-, and
AQ- generated by photoinduced
intermolecular electron-transfer reaction in MeCN is shorter than 15
ps. In the case of Pe-, the
uncomplete
ground-state recovery is ascribed to the occurrence of electron
photoejection. The free ion yield in the
intermolecular electron-transfer reaction between
9,10-dicyanoanthracene (DCA) and two electron
acceptors
was measured in a two-pulse experiment, where the second pulse excited
the ensuing DCA-. This
excitation
has no influence on the magnitude of the free ion yield, indicating a
short excited-state lifetime of
DCA-*
relative to the time scale of back electron transfer and ionic
dissociation. A red emission, ascribed to the
fluorescence of protonated Pe, was detected in boric acid glass and
sulfuric acid. No fluorescence that could
be clearly ascribed to Pe+* could be
observed.
