中文摘要：

β-苯基羰基化合物的光化学特征历来受到重视,是n,π＊羰基三线态猝灭机理的典型代表。研究了气相和甲醇中β-苄基苯乙酮的基态结构和激发态结构,模拟了其吸收和发射光谱,并从分子轨道角度阐明了其发光机制。研究发现：（1）在甲醇中,β-苄基苯乙酮的基态结构与气相结构非常接近,只是在羰基官能团附近键长有差别;（2）在甲醇中,β-苄基苯乙酮的S1态无法维持平面构型,且αC—C键显著拉长;（3）在气相中,β-苄基苯乙酮的吸收光谱很弱,而在甲醇中很强;（4）气相中,β-苄基苯乙酮的荧光光谱的发光机制与甲醇中不同;（5）在气相中,β-苄基苯乙酮荧光光谱的最大发射峰蓝移到228.67nm处,发射强度（f=0.306 1）比吸收光谱大幅增加;（6）从分子轨道角度看,荧光光谱是吸收光谱的逆过程;（7）在气相中,β-苄基苯乙酮的磷光光谱在252.58和246.04nm处有两个较强的发射峰,而甲醇中只在258.88nm处有一个很强的发射峰。

英文摘要：

The photochemistry of carbonyl compounds containingβ-phenyl rings has attracted increasing attention,for it is regarded as a representative template for the triplet n,π＊quenching of carbonyl groups.In gas phase and in methanol,the ground states and excitation states ofβ-benzylacetophenone were investigated and its absorption and emission spectra were simulated.Besides,the luminescence mechanisms were also elucidated from molecular orbitals.The theoretical results revealed that：（1）Its ground-state structure in methanol is very close to the geometry in gas phase except for the bond distances around the carbonyl group;（2）In methanol,the S1 state ofβ-benzylacetophenone can not maintain a planar configuration,and theαC—C bond is extended significantly;（3）The absorption spectrum ofβ-benzylacetophenone is very weak in gas phase,but it is very strong in methanol;（4）The fluorescence spectrum ofβ-benzylacetophenone in gas phase is also different from that in methanol;（5）In gas phase,the strongest emission peak of the fluorescence spectrum is blue-shifted to about 228.67 nm,and its oscillator strength（f=0.306 1）increases significantly;（6）The fluorescence spectrum is an inverse process of the absorption spectrum from the viewpoint of molecular orbitals;（7）In phosphorescence spectrum,there are two relatively strong emission peaks at252.58 and 246.04 nm in gas phase,but there is only one very strong emission peak at 258.88 nm in methanol.