Spectroscopic studies of two spectral variants of light-harvesting complex 2 (LH2) from the photosynthetic purple sulfur bacterium Allochromatium vinosum

► Femtosecond time-resolved spectroscopy of LH2 from Alc. vinosum. ► Carotenoid-to-bacteriochlorophyll a energy transfer. ► Femtosecond time-resolved spectroscopy of carotenoids. ► Explanation of mechanism of splitting of B800 bacteriochlorophyll a band in LH2. ► 77 K spectroscopy.