Time-Resolved Thermally Activated Delayed Fluorescence in C70 and 1,2-C70H2

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 104; no. 48; pp. 11265 - 11269
• Main Authors: Bachilo, Sergei M, Benedetto, Angelo F, Weisman, R. Bruce, Nossal, Jamie R, Billups, W. Edward
• Format: Journal Article
• Language: English
• Published: American Chemical Society 07.12.2000
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp002742k

Thermally activated delayed fluorescence (TDF) emission from C70 and 1,2-C70H2 has been time-resolved to provide thermodynamic and kinetic information on excited electronic states. The energy gap between S1 and T1 states was deduced from the temperature dependence of initial TDF intensities and independently from the ratio of TDF intensity to time-integrated prompt fluorescence. S1−T1 gaps were found to be approximately 2470 cm-1 for C70 and 2180 cm-1 for 1,2-C70H2, with relative uncertainties of 2−3%. Time-resolved TDF measurements from fullerene samples immobilized in PMMA films revealed lifetimes for triplet state decay unaffected by bimolecular deactivation processes. The intrinsic triplet lifetimes at 298 K were found from both TDF and transient absorption measurements to be 24.5 ± 1.5 ms for C70 and 1.95 ± 0.1 ms for 1,2-C70H2.