All-trans-β-carotene absorption shift and electron-phonon coupling modulated by solvent polarizability

Absorption, resonance Raman spectra are reported on all-trans-β-carotene dissolved in different polarizability solvents. The absorption spectra of all-trans-β-carotene are analyzed by Franck-Condon principle and the Huang-Rhys factors are calculated. With the increasing solvent polarizability, the Huang-Rhys factor and the electron-phonon coupling constant decrease, while the Raman scattering cross section increases. The red-shift of absorption would leads to an increasing spectral overlap with the laser excitation leading to an enhanced resonance effect. Through electron-phonon coupling, the ground state structure of all-trans-β-carotene will be modulated by the electronic transition and is assumed to lead to a modulation of energy flow. Results present insights on the solvent's polarizability dependence on electron-phonon coupling of carotenoid. This work is expected to be helpful for exploring the surrounding medium effects on the electronic transition and carbon‑carbon vibrations.