分子超激发态（激发波长113-60nm，能量11-20eV）光谱及其超快动力学是一个被研究得很少的领域，但是有重要的研究价值。本项目将从两方面开展研究：(1)利用从四波混频产生的高能量分辨极紫外激光泵浦分子到超激发态、紫外激光作探测光共振电离或饱和电离超激发态解离生成的里德堡态碎片，测量态分辨的产物信号强度随波长的变化；利用离子速度成像测量碎片的平动能分布和角分布；对含氢原子的分子，进一步利用延时时间曲线测量光解碎片H(2s)/H(2p)分支比。由此获得超激发态的归属、电子态-电子态相互作用等信息。（2）利用大连极紫外自由电子激光作泵浦光、钛宝石飞秒激光作探测光，测量母体分子离子信号、碎片离子速度成像、电子速度成像等随延时时间的变化，由此获得超激发态的衰变时间、衰变通道分支比等信息。结合两方面的研究结果全面认识典型小分子超激发态，包括O2、HCl、SO2、H2O和C2H2等。

Spectra and dynamics of molecular superexcited states (excitation photon energies 11-20 eV, wavelengths 113-60 nm) are very important to understand the highly excited molecular electronic states, however, not much studies have been performed. In this project, an XUV laser beam produced by four-wave mixing will be used to pump molecules to superexcited states, an UV laser beam to ionize the photofragments in Rydberg states using the REMPI or saturated ionization methods. The fragment yield spectra will be thus measured by tuning the excitation photon energies. The spatial distribution and translational energy distribution of the photofragments will be measured using velocity map imaging method. For molecules containing H atoms, we will measure the branching ratio H(2s)/H(2p) using delay-time-curve method. Based on the spectroscopic studies, the assignments of superexcited states and the interaction among different electronic states could be determined. On the other hand, we will study the femtosecond time-resolved decay dynamics of molecular superexcited states by employing the Dalian XUV free electron laser as the pump beam and a Ti-Sapphire laser as the probe laser beam. The delay dependence of the parent ion signals, the fragment yields, the fragment velocity map images, and electron map images will be measured. By combining the high resolution spectroscopic studies and the time-resolved studies, deep insights into the molecular superexcited states could be obtained. The molecules studied in this project are O2, HCl, SO2, H2O and C2H2, etc.