Correlation between the absorption spectra and resonance Raman excitation profiles of astaxanthin

Resonance Raman excitation profiles in the region 4579-5287 Å are reported for the carotenoid molecule astaxanthin at -162 and 23°C. At these temperatures the visible absorption spectra are structured and unstructured, respectively. The experimental data, simulated using a simple model, demonstrate that there is a correlation between the development of vibrational structure in the absorption spectrum and in the excitation profile. For astaxanthin the excitation profiles at room temperature do not resolve the vibrational structure of the broad absorption band but do show that the 0-0 transition occurs near 18 850 cm^-1.