苯胺分子S_1态振动光谱及ab initio计算(英文)

利用紫外激光,结合超声速脉冲分子技术和飞行时间质谱仪,在287～296 nm波长范围内实验研究了苯胺分子的共振双光子电离光谱(R2PI).实验中观测到对应S_1←S_0跃迁的0-0带出现在293.86nm(3.4029 cm~(-1))处,并测得对应S_1态的若干振动模和来自S_0态的热带.为了对S_1态的振动模进行标定,分别在HF/6-31+G(d,p)和CIS/6-31+G(d,p)基组水平上对苯胺在S_0态的构型进行优化和在S_1态对其振动频率进行分析计算.另外,利用自然键轨道分析(NBO)讨论了电子激发过程.结果显示,来自氨基氮原子上的一个电子从对应的孤对电子轨道激发到苯环的π反键轨道上,恰好对应的是S_1←S_0跃迁.

Vibrational spectrum of C6H5NH2 in S1 state and ab initio calculations

The resonant two-photon ionization (R2PI) spectrum of aniline has been measured by supersonic molecular technique with time-of-flight mass spectrometer in the laser wavelength range of 287 to 296 nm. The original band for S1←S0 transition appears at 293.86 nm (34029 cm-1) and some vibrational modes of the S1 state are observed. For giving an assignment to the vibrational modes in S1 state, ab initio calculations at HF/6-31+G(d, p) and CIS/6-31+G(d, p) basis set level were carried out for the geometric structure optimization and vibrational frequency analysis in S0 state and S1 state, respectively. Also the natural bond orbital (NBO) analyses are used to discuss the electron exciting process and the result indicates that the exciting of one electron from the lone pair orbital of nitrogen atom to the anti-bonding π orbital of the aromatic ring corresponding to the S1←S0 transition.