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Proceedings Paper

Kinetics and spectra of fullerene triplet states
Author(s): R. Bruce Weisman; Kevin D. Ausman; Angelo F. Benedetto; David A. Samuels
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Paper Abstract

Optical kinetic spectroscopy is used to investigate the triplet state properties of solution phase fullerenes. These triplet states, which are the molecules' lowest-energy and longest-lived electronic excitations, show lifetimes and absorption spectra that vary from fullerene to fullerene. In room temperature toluene solution, the intrinsic triplet lifetime of C70 exceeds that of C60 by a factor at of least 80. The 'self-quenching' deactivation of triplet states through encounters with ground state molecules occurs with rate constants of 1.6 X 1070 M-1s-1 for C60 and 3 X 107 M-1s-1 for C70. In solutions containing mixtures of fullerenes, transfer of triplet excitation between species is efficient and reversible, with rate constants up to 2 X 109 M-1s-1. When C60 is aliphatically derivatized at two adjacent sites to form (6,6)-closed dihydrofullerene structure, intrinsic triplet lifetimes are shortened by more than a factor of 3 to approximately 45 microsecond(s) . The triplet spectra of these compounds, in which the derivitizing groups are not sterically strained, are very similar to each other but significantly different from the C60 spectrum. The (6,6)-closed epoxide, C60O, displays unusual triplet state behavior. Its initial triplet spectrum is distinct from that of the other derivatives studied and decays in approximately 6 microsecond(s) through nonexponential kinetics. Evolution of the induced spectrum suggest the possibility of epoxide ring opening form the triplet state of C60O.

Paper Details

Date Published: 1 November 1997
PDF: 10 pages
Proc. SPIE 3142, Fullerenes and Photonics IV, (1 November 1997); doi: 10.1117/12.279253
Show Author Affiliations
R. Bruce Weisman, Rice Univ. (United States)
Kevin D. Ausman, Rice Univ. (United States)
Angelo F. Benedetto, Rice Univ. (United States)
David A. Samuels, Rice Univ. (United States)

Published in SPIE Proceedings Vol. 3142:
Fullerenes and Photonics IV
Zakya H. Kafafi, Editor(s)

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