Low-lying singlet states of carotenoids having 8–13 conjugated double bonds as determined by electronic absorption spectroscopy

Electronic absorption spectra were recorded at room temperature in solutions of carotenoids having different numbers of conjugated double bonds, n = 8–13, including a spheroidene derivatives, neurosporene, spheroidene, lycopene, anhydrorhodovibrin and spirilloxanthin. The vibronic states of 1 B u + ( v = 0 – 4 ) , 2 A g - ( v = 0 – 3 ) , 3 A g - (0) and 1 B u - (0) were clearly identified. The arrangement of the four electronic states determined by electronic absorption spectroscopy was identical to that determined by measurement of resonance Raman excitation profiles [K. Furuichi et al., Chem. Phys. Lett. 356 (2002) 547] for carotenoids in crystals.