溴乙烷分子的质量分辨阈值光谱

利用单色双光子(1C2P)技术得到了高精度的溴乙烷分子的质量分辨阈值(MATI)光谱，精确给出了溴乙烷分子的绝热电离势和离子振动频率.从中性基态到离子基态两个自旋-轨道分量X₁ ²E_1/2和X₂ ²E_1/2的绝热电离势分别为83097±3 cm^-1和85452±3 cm^-1，离子基态两个自旋-轨道分量的间隔为2355±6 cm^-1，这些值与文献报道值符合得较好，且精度更高.溴乙烷分子的单色双光子质量分辨阈值光谱展现出丰富的振动结构，这是在溴乙烷分子相继吸收两个光子的过程中波包在解离态势能面上演化的结果.以已有的离子振动谱标识为参考，以中性分子的振动频率为基础，标识了溴乙烷分子的质量分辨阈值光谱，发现观测到的振动模几乎都和溴乙烷分子的解离运动有关，其中还包括一些非全对称模. 关键词： 质量分辨阈值光谱 振动模 单色双光子零动能光谱技术 溴乙烷

Mass analyzed threshold ionization spectra of ethyl bromide

Using one-color two-photon (1C2P) scheme, high-resolution mass analyzed threshold ionization MATI spectra of ethyl bromide have been recorded. Accurate values for the adiabatic ionization energy have been determined to be 83097±3 cm^-1 and 85452±3 cm^-1 for the X₁ ²E_1/2 and X₂ ²E_1/2 states of the cation， respectively, giving a splitting of 2355±6 cm^-1. The ionic vibrational frequencies were also obtained, and the values were in agreement with high accuracy with the literature data. The spectra showed extensive excited vibrational structure as a result of wave packet evolving on the potential energy surface of the dissociative state in the time interval between the absorption of the two photons. The vibrational calibration was done based on the known vibrational frequencies of the neutral ethyl bromide. The spectrum was found to exhibit mainly vibrational modes involving the dissociation of the molecule, including some non-totally symmetric modes.