Nuclear motion and dissociation dynamics of core-excited molecules

利用安装在同步辐射装置上的高分辨率单色器获得的单色软X射线，研究了核激发分子的核运动和解离动力学。主要结果如下：(1)首次在H_2O分子的O_1S激发光谱中解析出了VivRational结构。结果表明，O_1s^&lt；-1&gt；2b_2激发态存在一个势极小值，随着O_1s^&lt；-1&gt；2b_2激发态能量的增加，俄歇衰变后H_2^离子的生成量增加。研究还发现，通过在1s→2b_2共振范围内调节激发能，可以显著地控制俄歇末态1b_2^&lt；-1&gt；的核运动。(2)由于静态Renner-Teller效应，CO_2的双简并核激发的II态分裂为两个态。利用三离子符合动量成像技术，对B_1和A_1 Renner-Teller对的线性和弯曲几何构型分别进行了直接和单独的探测，重点研究了测量量与入射光偏振的关系。此外，利用对称分辨、振动分辨激发谱研究了B_1和A_1态之间的动力学耦合。(3)BF_3平面分子在D&lt；3h&gt；用角度分辨离子产额谱、共振俄歇电子能谱和四离子符合动量成像技术研究了B_1S到2a_2“激发引起的对称性.(4)通过测量F离子的各向异性碎裂和F原子在核激发后到俄歇衰变前超快分子碎裂产生的多普勒频移的各向异性俄歇发射，研究了F_4和SiF_4分子在F_1s到2T_2”激发下T_d对称性的非对称核运动.

Nuclear motion and dissociation dynamics of core-excited molecules have been investigated using monochromatic soft X-rays obtained from the high-resolution monchromators installed in the synchrotron radiation facilities. Major results can be summarized as follows.(1) Vivrational structure have been resolved in the O 1s excitation spectrum of H_2O molecules for the first time. It was found that the O 1s^<-1> 2b_2 excited state has a potential minimum and that H_2^+ ion formation after the Auger decay increases with the increase in energy stored in the O 1s^<-1> 2b_2 excited state. It was also found that the nuclear motion of the Auger final 1b_2^<-1> state can be controlled significantly by tuning the excitation energy within the 1s→2b_2 resonance.(2) The doubly-degenerate core-excited II state of CO_2 splits into two due to static Renner-Teller effect. The linear and bent geometries for the B_1 and A_1 Renner-Teller pair states have been probed directly and separately, using the triple-ion-coincidence momentum imaging technique and focusing on the dependence of the measured quantities on the polarization of the incident light. Furthermore dynamical coupling between B_1 and A_1 state were investigated using symmetry-resolved, vibrationally-resolved excitation spectra.(3) The out-of-plane nuclear motion of the BF_3 planar molecule in D_<3h> symmetry induced via B 1s to 2a_2" excitation has been probed by angle-resolved ion yield spectroscopy, resonant Auger electron spectroscopy and quadruple-ion coincidence momentum imaging technique.(4) The asymmetric nuclear motion of the CF_4 and SiF_4 molecule in T_d symmetry induced via F 1s to 2t_2" excitation has been investigated by measuring the anisotropic fragmentation of the F+ ion and the Doppler-shifted anistoropic Auger emission from thedeparting F atom produced via the ultrafast molecular fragmentation of the molecule after the core-excitation but before the Auger decay.