Femtosecond-picosecond laser photolysis studies on the dynamics of excited charge-transfer complexes: Aromatic hydrocarbon-acid anhydride, -tetracyanoethylene, and -tetracyanoquinodimethane systems in acetonitrile solutions

Journal Article · Thu Mar 07 00:00:00 EST 1991 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100158a014· OSTI ID:5678932

Asahi, Tsuyoshi; Mataga, Noboru ^[1]

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1. Osaka Univ. (Japan)

Formation processes of contact ion pairs (CIP) from the excited Franck-Condon (FC) state of charge-transfer (CT) complexes of aromatic hydrocarbons with acid anhydride as well as cyano compound acceptors in acetonitrile solution and charge recombination (CR) rates (k{sub CR}{sup CIP}) of produced CIP states have been investigated by femtosecond and picosecond laser phototlysis and time-resolved absorption spectral measurements covering a wide range of free energy gap-{Delta}G{degree}{sub ip} between the ion pair and the ground state. It has been confirmed that the CIP formation becomes faster and k{sub CR}{sup CIP} of the produced CIP increases with increase of the strengths of the electron donor (D) and acceptor (A) in the complex, i.e., with decrease of the {minus}{Delta}G{degree}{sub ip} value. This peculiar energy gap dependence of k{sub CR}{sup CIP}, quite different from the bell-shaped one observed in the case of the solvent-separated ion pairs (SSIP) or loose ion pairs (LIP) formed by encounter between fluorescer and quencher in the fluoresence quenching reaction, has been interpreted by assuming the change of electronic and geometrical structures of CIP depending on the strengths of D and A.

• OSTI ID: 5678932
• Journal Information: Journal of Physical Chemistry; (USA), Vol. 95:5; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ETHYLENE
PHOTOLYSIS
QUINOLINES
ABSORPTION SPECTROSCOPY
ACETONITRILE
ANHYDRIDES
DATA ANALYSIS
EXCITED STATES
FRANCK-CONDON PRINCIPLE
ION PAIRS
ALKENES
AROMATICS
AZAARENES
AZINES
CHEMICAL REACTIONS
DECOMPOSITION
ENERGY LEVELS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PYRIDINES
SPECTROSCOPY
400500* - Photochemistry