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Updated: Jun 12, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Competing ultrafast intersystem crossing and internal conversion in the "channel 3" region of benzene
R S Minns1, D S N Parker, T J Penfold
1Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
Abstract:
We report new, detailed, femtosecond time-resolved photoelectron spectroscopy experiments and calculations investigating the competition between ultrafast internal conversion and ultrafast intersystem crossing in electronically and vibrationally excited benzene at the onset of "channel 3". Using different probe energies to record the total photoelectron yield as a function of pump-probe delay we are able to confirm that S(1), T(1) and T(2) electronic states are involved in the excited state dynamics. Time-resolved photoelectron spectroscopy measurements then allow us to unravel the evolution of the S(1), T(1) and T(2) components of the excited state population and, together with complementary quantum chemistry and quantum dynamics calculations, support our earlier proposal that ultrafast intersystem crossing competes with internal conversion (Chem. Phys. Lett., 2009, 469, 43).
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