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

Fujiwara, M., Yamauchi, K., Sugisaki, M., Gall, A., Robert, B., Cogdell, R.J. and Hashimoto, H. (2008) Energy dissipation in the ground-state vibrational manifolds of beta-carotene homologues: a sub-20-fs time-resolved transient grating spectroscopic study. Physical Review B, 77(20), p. 205118. (doi: 10.1103/PhysRevB.77.205118)

Abstract

Transient grating (TG) signals in 8-carotene homologues, by using sub-20-fs excitation pulses, were measured in order to investigate the dependence of the vibrational coherence dynamics on the pi-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

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Cogdell, Professor Richard
• Authors: Fujiwara, M., Yamauchi, K., Sugisaki, M., Gall, A., Robert, B., Cogdell, R.J., and Hashimoto, H.
• Subjects: Q Science > QC Physics
• College/School: College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
• Journal Name: Physical Review B
• Publisher: American Physical Society
• ISSN: 1098-0121
• ISSN (Online): 1550-235X