Electron configuration changes in excited pyrazine molecules analyzed by femtosecond time-resolved photoelectron spectroscopy
Electron configuration changes in excited pyrazine molecules analyzed by femtosecond time-resolved photoelectron spectroscopy
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DOI：
10.1063/1.481008
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发表时间：
2000-02
影响因子：
4.4
通讯作者：
V. Stert;P. Farmanara;W. Radloff
中科院分区：
文献类型：
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作者：
V. Stert;P. Farmanara;W. Radloff
利用泵浦-探测技术研究了吡嗪分子在200 nm和266 nm附近的130 fs激光脉冲激发下到S_2态的内转换。S2态由于内转换到低电子态的寿命为τIC（2）=（20±10）fs，而二次布居的S1态的寿命为τIC（1）=（22±1）ps.飞秒时间分辨电子能谱的结果直接反映了内转换过程中电子构型的变化：内转换后，经ππ* 构型的S2态电离和经nπ* 构型的S1态电离产生的吡嗪离子的电子能谱在fs时间尺度上发生了显著变化.所获得的结果证实了Domcke及其同事的理论估计[J. Chem. Phys. 95，7806（1991）; J. Phys. Chem. 97，12466（1993）]，他们描述了吡嗪分子中的内转换，其基础是两个分子的圆锥相交。
Using the pump–probe technique with 130 fs laser pulses near 200 nm and near 266 nm the internal conversion of the pyrazine molecule excited to the S2 state has been studied. The lifetime of the S2 state due to internal conversion to the lower electronic states is τIC(2)=(20±10) fs while the lifetime of the secondarily populated S1 state is τIC(1)=(22±1) ps. The results of femtosecond time-resolved electron spectroscopy directly demonstrate the variation of the electron configuration during the internal conversion: The electron spectrum changes significantly on the fs time scale for pyrazine ions produced by ionization via the S2 state with ππ* character and by ionization of S1 state molecules with nπ* configuration after the internal conversion, respectively. The results obtained confirm theoretical estimations of Domcke and co-workers [J. Chem. Phys. 95, 7806 (1991); J. Phys. Chem. 97, 12466 (1993)] who describe the internal conversion in the pyrazine molecule on the basis of a conical intersection of t...