Liu Min, Jiang Pan, Cheng Min, Gao Hong
Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
J Chem Phys. 2021 Dec 21;155(23):234305. doi: 10.1063/5.0072604.
In this study, we employed a newly built time-slice velocity-map ion imaging setup, equipped with two tunable vacuum ultraviolet (VUV) laser sources, to obtain the first comprehensive high-resolution photoexcitation and photofragment excitation spectra of NN in the VUV photon energy range 109 000-117 500 cm. The spectroscopic simulation program PGOPHER was used to analyze the rotationally resolved spectra. Band origins, rotational constants, and isotope shifts compared with those of N have been obtained for 31 electric-dipole-allowed vibrational states of NN in the aforementioned energy range. These spectroscopic parameters are found to depend on the vibrational quantum number irregularly. Systematic perturbations of the rotational transition energies and predissociation rates within individual absorption bands have also been observed. These are proved to be caused by the strong homogeneous interactions between the valence b'Σ state and the Rydberg c Σ states, and between the valence bΠ states and the Rydberg o Π states. Heterogeneous interactions between the Rydberg c Π states and c Σ states also play an important role.
在本研究中，我们采用了一种新构建的时间切片速度映射离子成像装置，该装置配备了两个可调谐真空紫外（VUV）激光源，以获取在109000 - 117500厘米的VUV光子能量范围内NN的首个全面的高分辨率光激发和光碎片激发光谱。使用光谱模拟程序PGOPHER分析了转动分辨光谱。在上述能量范围内，已获得了NN的31个电偶极允许振动状态的带起源、转动常数以及与N相比的同位素位移。发现这些光谱参数不规则地依赖于振动量子数。还观察到了各个吸收带内转动跃迁能量和预解离速率的系统微扰。事实证明，这些是由价b'Σ态与里德堡cΣ态之间以及价bΠ态与里德堡oΠ态之间的强均匀相互作用引起的。里德堡cΠ态与cΣ态之间的非均匀相互作用也起着重要作用。
