Issue 31, 2010

Assignment of caroteneS* state features to the vibrationally hot ground electronic state

Abstract

The so-called S* state has been suggested to play an important role in the photophysics of β-carotene and other carotenoids in solution and photosynthetic light-harvesting complexes, yet its origin has remained elusive. The present experiments employing temperature-dependent steady-state absorption spectroscopy and ultrafast pump-supercontinuum probe (PSCP) transient absorption measurements of β-carotene in solution demonstrate that the spectral features of S* are due to vibrationally excited molecules in the ground electronic state S0. Characteristic spectral signatures, such as a highly structured bleach below 500 nm and absorption in the range 500–660 nm result from the superposition of hot S0 absorption (“S0*”) on top of the ground-state bleach of room-temperature molecules. Appearance and disappearance of the S0* molecules can be completely described by a global kinetic analysis employing time-dependent species-associated spectra without the need to invoke the population of an intermediate electronically excited state.

Graphical abstract: Assignment of carotene S* state features to the vibrationally hot ground electronic state

Supplementary files

Article information

Article type
Paper
Submitted
30 Nov 2009
Accepted
09 Apr 2010
First published
07 Jun 2010

Phys. Chem. Chem. Phys., 2010,12, 8832-8839

Assignment of carotene S* state features to the vibrationally hot ground electronic state

T. Lenzer, F. Ehlers, M. Scholz, R. Oswald and K. Oum, Phys. Chem. Chem. Phys., 2010, 12, 8832 DOI: 10.1039/B925071A

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