C[sub 70] triplet excimers: evidence from transient absorption kinetics

Journal Article · Thu Mar 02 04:00:00 EST 1995 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100009a038· OSTI ID:6563717

Etheridge, III, H T; Weisman, R B ^[1]

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1. Rice Univ., Houston, TX (United States)

Time-resolved absorption measurements on solutions of pure C[sub 70] in toluene reveal complex kinetics that vary strongly with sample concentration and probe wavelength. These observations suggest efficient association between triplet and ground state C[sub 70] molecules to form triplet excimers. Decay data measured with sample concentrations near and below 1 [mu]M show that the intrinsic lifetime of the C[sub 70] triplet monomer is at least 12 ms. Data at higher sample concentrations are fit by a kinetic model in which triplet monomers rapidly preequilibrate with shorter-lived excimers, causing strong apparent self-quenching of the triplet excitation. The rate constants for excimer formation, dissociation, and deactivation in this model are deduced to be approximately 10[sup 9] M[sup [minus]1] s[sup [minus]1], 10[sup 5] s[sup [minus]1], and 10[sup 4] s[sup [minus]1], respectively. Because the equilibrium constant for association lies near 10[sup 4] M[sup [minus]1], many photoexcited solutions of C[sub 70] may be expected to contain not only monomer, as normally assumed, but also significant concentrations of excimer. 29 refs., 7 figs.

• OSTI ID: 6563717
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 99:9; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ALKYLATED AROMATICS
AROMATICS
CARBON
CHEMICAL REACTIONS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
FULLERENES
HYDROCARBONS
LASERS
LIFETIME
MONOMERS
MULTIPLETS
NONMETALS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
TOLUENE
TRIPLETS