Excited-state dynamics of the 1Bu+,3Ag−, and 1Bu− states in a carotenoid molecule by 5-fs absorption spectroscopy

The time-resolved absorption spectra of all-trans-spirilloxanthin were recorded by the use of extremely stable sub-5-fs pulses covering coherently the main visible range of 520–700 nm. All the theoretically predicted and long-lasting argued states (image, image, and image states) were clearly identified for the first time. The spectrum of each component and lifetime were determined without ambiguity by the global fitting method. Their lifetimes were in sequence ∼10, 25±2, and 140±30 fs.