Energy dissipation in the ground-state vibrational manifolds of β -carotene homologues: A sub-20-fs time-resolved transient grating spectroscopic study

Masazumi Fujiwara, Kensei Yamauchi, Mitsuru Sugisaki, Andrew Gall, Bruno Robert, Richard J. Cogdell, Hideki Hashimoto

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

Transient grating (TG) signals in β -carotene homologues, by using sub-20-fs excitation pulses, were measured in order to investigate the dependence of the vibrational coherence dynamics on the π -conjugation length of these carotenoids. The experimental TG traces can be well reproduced by computational simulations based on a Brownian oscillator model using the spectral density determined from their respective resonance Raman spectra and their previously reported excited-state population-relaxation times. The total dephasing times of the ground-state vibrational modes of the homologues were determined by applying a wavelet transformation of their coherent oscillations, which were observed in the experimental TG traces. The total dephasing time decreases as the number of conjugated C=C double bonds increases. The decoherence of the ground-state vibrational modes in the homologues is mainly caused by system-bath interactions. The dephasing time of the C-C stretching modes strongly depends on the conjugation length, whereas that of the C=C stretching does not. This trend clearly shows that shorter-chain carotenoids have a specific major channel of energy dissipation to the environment (the C=C stretching), whereas the longer-chain carotenoids do not.

Original languageEnglish
Article number205118
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume77
Issue number20
DOIs
Publication statusPublished - May 21 2008
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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