Effect of pressure and solvent on Raman spectra of all-trans-beta-carotene.
The ground state Raman spectra of all-trans-beta-carotene in n-hexane and CS2 solutions are measured by simultaneously changing the solvent environment and molecular structure under high hydrostatic pressure. The diverse pressure dependencies of several representative Raman bands are explained using a competitive mechanism involving bond length changes and vibronic coupling. It is therefore concluded that (a) the in-phase C=C stretching mode plays an essential role in the conversion of energy from S1 to S0 states in carotenoids, (b) internal conversion and intramolecular vibrational redistribution can be accelerated by high pressure, and (c) the environmental effect, but not the structural distortion or pi-electron delocalization, is responsible for the spectral properties of a given carotenoid species. These findings revealed the potential of high pressure in exploring the nature of the biological functions of carotenoids.
Liu
Wei-Long
WL
Center for Condensed Matter Science and Technology, Harbin Institute of Technology, Harbin 150001, China.
Zheng
Zhi-Ren
ZR
Zhu
Rui-Bin
RB
Liu
Zhi-Guo
ZG
Xu
Da-Peng
DP
Yu
Hua-Min
HM
Wu
Wen-Zhi
WZ
Li
Ai-Hua
AH
Yang
Yan-Qiang
YQ
Su
Wen-Hui
WH
D001703:Biophysics / Q000379:methods; D002338:Carotenoids / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods; D006586:Hexanes / Q000737:chemistry; D008956:Models, Chemical; D015233:Models, Statistical; D011312:Pressure; D013050:Spectrometry, Fluorescence / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014732:Vibration; D019207:beta Carotene / Q000737:chemistry*
D006586:Hexanes; D019207:beta Carotene; D002338:Carotenoids