Abstract: In this work, the two isomers of benzil, cis-skewed(c-S) and trans-planar(t-P) configurations, were optimized both in gas phase and in solution. Based on the corresponding optimal structures, the absorption and emission spectra are discussed at the level of TD-B3LYP/6-31+G^*. The polarizable continuum model is applied in the calculations in solution. The calculated results indicate that the cis-skewed configuration is slightly favored when the polarity of the solvent increases. T₁ and S₁ states of the two isomers as well as S₂ state of the cis-skewed configuration all arise from the local excitation of n→π^*

Key words: Excitation state, Absorption and emission spectra, Solvent effects, Stocks shift