N2O+离子A2Σ+电子态的光解动力学研究

用一束波长为360.55nm的激光，通过N2O分子的（3+1）共振多光子电离（REMPI）过程制备纯净且布居完全处于X2Π(000)态的母体离子N2O+，然后用另一束波长在275—328nm范围内的可调谐激光将制备的N2O+离子激发至预解离电子态A2Σ+.实验发现，由于解离碎片NO+所具有的一定的反冲速度，其TOF质谱峰明显比N2O+母体宽.通过分析NO+碎片TOF质谱峰形状，得到了解离产物的总平均平动能〈ET〉；通过考察〈ET〉随光解能量的变化，发现光解能量在32000cm-1附近约250cm-1的变化 关键词： N2O+离子A2Σ+态 TOF质谱峰 预解离机理

Photodissociation study of N2O+（A2Σ+） ions

Pure parent ions, N2O+, populated at X2Π(000), were prepared by (3+1) multiphoton ionization of jet cooled N2O molecules at 360.55nm, and then were excited to different vibrational levels of predissociative A2Σ+ state by another laser in the wavelength range of 275—328nm. The total released translational energies 〈ET〉 at different excitation energies were measured with a time of flight (TOF) spectrometer from the TOF broadenings of the NO+ fragment.The 〈ET〉value drops abruptly from ～8000cm-1 to ～1600cm-1 at excitation energy of ～32000cm-1.Further analysis shows that at the excitation energies below 32000cm-1, the dissociation channel is NO+(X1Σ+)+N(4S), and at the energies above 32000cm-1 a new channel, NO+(X1Σ+)+N(2D), is opened and replaces completely the N(4S) channel. The predissociation mechanism of the N2O+(A2Σ+) ions was discussed based on the experimental results.