对甲氧基苯乙腈的REMPI和MATI光谱模拟

Spectral Simulation of REMPI and MATI for p-Methoxyphenylacetonitrile

采用密度泛函理论(B3LYP/aug-cc-pVDZ)计算了对甲氧基苯乙腈的基态S_(0)、第一电子激发态S_(1)和离子基态D_(0)的稳定构型,结果表明对甲氧基苯乙腈存在cis和trans两种稳定旋转异构体,cis构型基态的能量比trans低约89 cm^(-1)。如此相近的能量预示了在超声分子束中两种异构物可能共存。对两种异构体从基态到激发态的共振多光子电离(REMPI)光谱和激发态到离子基态的电子振动光谱或质量分辨阈值电离(MATI)光谱进行了理论模拟,分析了各振动带的振动模式,为实验测量和分析提供了重要参考数据。

The stable geometries of the ground state S_(0),the first electronic excitedstate S_(1)and the ionic ground state D_(0)of the pmethoxyphenylacetonitrile at B3LYP/aug-cc-PVDZ level are calculated.Both cis and transrotamers are found to be stable.The cis ratamer is lower 89cm^(-1)than the trans one in energy.Such a similar energy indicates that the two rotamers in the supersonic molecule beam may coexist.The resonance multiphoton ionization(REMPI)and mass analyzed threshold ionization(MATI)spectra are simulated for these two rotamers.The vibrational bands observed in the spectra were assigned.These works provide important data for REMPI and MATI experiments.