Study of molecule spectra of carotenoid

Carotenoid is a short-chain polyene biomolecule of 9 CC conjugate double-bonds. Due to its special structure carotenoid is used not only in photoprotection and anti-cancer, but also in molecule wires, light switch, and light filter. In this paper molecule spectra of carotenoid are studied. The carotenoid has the broadband fluorescence, the broadband stimulated Raman scattering is obtained when the fluorescence of carotenoid is used to enhance stimulated Raman scattering. Electron energy gap of carotenoid becomes narrow with temperature decreasing, and absorption spectra are red-shifted. These characteristics can make the carotenoid a high-quality semiconductor component. Raman active is intensive and the 3rd order optical nonlinear coefficient is large. The Raman scattering cross section of CC bond is about 10 orders of magnitude larger than that of common molecule. The Raman scattering intensity of overtone is intensive: the ratio of overtone to basic frequency is around 0.5 at low temperature. These spectrum characteristics of carotenoid are significant for studying polyene molecule structure, property and non-biology domain.