Retinal shows its true colours: Photoisomerization action spectra of mobility-selected isomers of the retinal protonated Schiff base

Abstract

Retinal is one of Nature's most important and widespread chromophores, exhibiting remarkable versatility in its function and spectral response, depending on its protein environment. Reliable spectroscopic and photochemical data for the isolated retinal molecule are essential for calibrating theoretical approaches that seek to model retinal's behaviour in complex protein environments. However, due to low densities and possible co-existence of multiple isomers, retinal is a challenging target for gas-phase investigations. Here, the photoisomerization behaviour of the trans isomer of the retinal protonated Schiff base (RPSB) is investigated in the gas phase by irradiating mobility-selected RPSB..