Direct observation of the S1 level of the carotenoid spheroidene using near-infrared femtosecond spectroscopy
In this work, we have determined the energy of the S1 state of the carotenoid spheroidene. The energy of this state is 13,400 ± 90 cm-1 at both 293 K and 186 K, showing that there is no temperature-induced shift of the S1 level. A discrepancy of about 800 cm-1 between the S1 energy determined here and that obtained from previous fluorescence and resonance Raman measurements is explained in terms o
