The dynamics of the ultraviolet (UV) photoexcitation of methyl nitrite in weakly interacting perfluoromethylcyclohexane solution are investigated using transient absorption spectroscopy. UV excitation in the structured S1 ← S0 absorption band induces dissociation, with geminate recombination and vibrational cooling of syn and anti-conformers of methyl nitrate on a timescale of ∼56 ps. Solvent-induced vibrational cooling favours relaxation to the higher-energy anti-conformer on entropic grounds, and subsequent inter-conversion to the lower-energy syn-conformer is prevented by a 3500 cm–1 barrier. UV excitation to the S2S2 state produces a transient electronic absorption band resembling the absorption spectrum of NO2.
Coulter, P. M., Grubb, M. P., & Orr-Ewing, A. J. (2017). Conformer-specific geminate recombination following methyl nitrite photolysis in solution. Chemical Physics Letters, 683, 416-420. https://doi.org/10.1016/j.cplett.2017.01.068