Effect of Temperature on the Raman Spectrum of Short-chain Polyenes Biological Molecules beta-Carotene

Raman spectra of beta-carotene with 9 conjugated double bonds polyenes bioligical molecules were measured in dimethyl sulfoxide(DMSO) solution, at temperature range from 298 K to 346 K(25-73 degrees C) in this experiment by Gobin Yvon hr800 Raman spectrometer commreted Linkam, Thms600 heating device. The results show that short-chain polyenes biological molecules beta-carotene have larger Raman scattering cross section[6.5x10(-23) cm(2)/(molecule . Sr)]. Besides resonance effect, the molecular structural order of beta-carotene, which can generate coherent weak damping C-C bond vibration is an important factor, can lead to high Raman scattering cross section. The temperature has great effect on polyenic linear molecular structural order. Due to the temperature increases, the molecular structural order of beta-carotene decreases, which lead to the weak of coherent weakly damping C-C bond vibration, the C-C bond length changes short. Because the C-C bond length is slightly different, the Raman scattering cross section decreases. And the frequency shifts towards higher frequencies, the frequency components of vibration increase, and the Raman linewidth becomes broadened.