Resonance Raman features all-trans-β-carotene during phase transition and theoretical investigation analysis

Abstract

Raman and absorption features all-trans-β-carotene (β-Car) liquefied in dimethyl sulfoxide (DMSO) of 10−6 concentration at temperature range from 333K to 263K are recorded. The usage of density functional theory (DFT) calculations could meticulously anticipate the molecular vibration mechanism. The calculation of CC bond length alternation (BLA) and graphic illustration of the highest occupied molecular orbital (HOMO) of β-Car can help decipher the vibration mechanism during phase transition. The Raman scattering cross section (RSCS) of the CC single and double bonds roughly increases when temperature decreases during pure liquid- solid phase condition due to extended effective conjugation length (ECL). The RSCS sharply drops during the phase transition because the β rings are very likely rotated from 0° to 90°. Electronic transition energy (0-0) of absorption spectra declining lead to the amplified resonance effect. This research is counted upon to be valuable by using DFT calculations to investigate the influence of phase transition on resonance Raman character of β-Car.