281—332nm SO+2的光碎片激发谱研究

在超声分子束条件下，利用380.85nm的电离激光使SO₂分子经由［３＋１］共 振增强多光 子电离(REMPI)制备纯净的分子离子SO⁺₂(²A ₁(000))，用另一束解离激光在281 —332nm扫描获得了光解碎片激发(PHOFEX)谱.获得的光碎片SO⁺激发谱基本可以 归属为SO ⁺₂(,)←SO⁺关键词： +₂')" href="#">SO⁺₂ 光解离 光碎片激发谱

Study on the photofragment excitation spectrum of SO+2 in the range of 281-332nm

With the preparing of SO⁺₂(²Ａ₁( 000)) by ［3+1］ multiphoton ioniz ation of the neutral SO₂ molecules at 380.85nm,the photofragment exci tation (P HOFEX) spectrum in ultraviolet (UV) (281-332nm) wavelength range has been obtain ed.The PHOFEX spectrum in the UV range was assigned essentially to the SO^{+< /sup>₂(,)←SO+₂(2Ａ₁) transitions.The transitions fr om 2Ａ₁(000) to the bend vibration levels of SO+< /sup>₂() were suggested,new harmon ic bend vibrational frequency ν₂=241.78±0.92cm-1 and the anharmonicity constant X₂₂=-1.71±0.01cm-1 for SO+_{2() was deduced.By using th e SO+ PHOFEX spectra in UV and in visible range (562-664nm), the symm etry of ,, states of SO+2 and the predissociation mechanism of SO< sup>+2}(,,) were determined,that is,(i)the symmetry of ,, states of SO+₂ s hould be 2 B₂，2Ｂ₁，2Ａ₁，( ii) around ,, states there should be two r epulsive states of symmetry α2Ａ₂ and β2Ｂ₂，converging to the dissociation limit of SO+(X2П)+O(3Pg),(iii)the couplings betw een 2B₁ and α2A₂ and betwee n 2 B₂ and β2Β₂,lead to the dissociation to S O+(X2П)+O(3Ｐ_g).}