Vibrational and electronic spectroscopy of the retro-carotenoid rhodoxanthin in avian plumage, solid-state films, and solution.

Highlights: [•] Resonance Raman spectra of rhodoxanthin, a retro-carotenoid, are reported. [•] Spectra of rhodoxanthin in feathers are compared with those of the isolated pigment. [•] Vibrational spectra are compared with electronic structure calculations. [•] The absorption of rhodoxanthin in feathers is probed via reflectance spectroscopy. [•] Shifts in absorption of rhodoxanthin are attributed to excited-state perturbations. [ABSTRACT FROM AUTHOR]