Action and Ion Mobility Spectroscopy of a Shortened Retinal Derivative.

The development of tandem ion mobility spectroscopy (IMS) known as IMS-IMS has led to extensive research into isomerizations of isolated molecules. Many recent works have focused on the retinal chromophore which is the optical switch used in animal vision. Here, we study a shortened derivative of the chromophore, which exhibits a rich IM spectrum allowing for a detailed analysis of its isomerization pathways, and show that the longer the chromophore is, the lower the barrier energies for isomerization are. Graphical Abstract.

The UV-visible action-absorption spectrum of all-trans and 11-cis protonated Schiff base retinal in the gas phase.

The UV-visible absorption of retinal in its protonated Schiff-base form is studied in the gas phase. In particular, transitions to highly-excited electronic states, Sn, in the all-trans and 11-cis forms are considered, and several new states are discovered. Their positions and strengths are compared to state of the art quantum calculations. The location of these states are particularly important when new fs pump-probe experiments are designed to investigate the fast excited-state dynamics of retinal chromophores.