双原子分子F2，N2和CO的解离能对检验高精度分子电子结构计算尤其是电子相关能的计算方法有重要意义，也在CODATA的数据库中被列为关键热力学数据。对于F2，N2和CO分子，现有的测量精度分别为 8，8 和80 cm-1，其中有关F2的数据是由申请人小组利用离子对产生效率谱所测量。在本项目中，申请人将利用新的超激发态分子光谱方法测量这三个分子的解离能，将其精度提高到1 cm-1 或光谱精度。对于F2和CO分子, 我们将用XUV激光或 UV+XUV两束激光分步激发分子到离子对Rydberg态，通过测量阈值离子对产生光谱来测量它们的解离能。 对于N2分子, 我们将用 XUV+UV两束激光分步激发分子到超激发态并利用UV激光将碎片电离，通过测量超激发态解离碎片产生效率谱和速度成像来测量它的解离能。另外，这三个分子的超激发态光谱及动力学也将得到深入的研究。

The bond dissociation energies of F2, N2 and CO are benchmarks for high precision molecular electronic structure calculations, and are fundamental importance in thermodynamics, which are listed as the key values of the thermodynamics in the CODATA database. For F2 and N2, the present reported uncertainties are about 8 cm-1 . For CO, the present reported uncertainty is worse than 80 cm-1 (10 meV). The applicant of this project has determined precisely the bond dissociation energy of F2 (8 cm-1) using a combination of XUV laser, velocity map imaging and ion-pair photodissociation techniques. In this proposal, the applicant will apply new experimental techniques and spectroscopic methods to measure the bond dissociation energies of the three molecules and improve the precision to 1 cm-1. For F2 and CO, we will measure their threshold ion-pair production spectra using XUV laser or a combination of XUV+ UV two laser beams. For N2, we will excite the molecule to superexcited states using a combination of XUV and UV laser beams. By measuring the predissociation yield spectra and the velocity map images of the fragments, the bond dissociation energy of N2 can be measured at a precision of 1 cm-1. The spectra and dynamics of the super-excited states of the three molecules will also be studied thoroughly.