Perturbation of the benzil ground and excited state geometries at low temperatures in hydrocarbon glasses

Abstract

The benzil phosphorescence in methylcyclohexane (MCH) and isopentane (IP) glasses is dominated by emission from the benzil crystal at concentrations > 10^–4 M, below which the phosphorescence from monomeric species is: MCH, λ_max 580 nm from T₁-planar→S₀ planar, and IP, λ_max 530 nm from T₁-skewed→S₀-skewed; excitation spectra show that the absorbing geometry of the absorbing ground state species is planar in MCH but skewed in IP.