物理化学学报 >> 2012, Vol. 28 >> Issue (04): 963-970.doi: 10.3866/PKU.WHXB201202162

光化学和辐射化学 上一篇    下一篇

OCS+经由A2ПX2П激发的光解离光谱

周丹娜, 陈琳, 吴丹, 张立敏   

  1. 中国科学技术大学化学物理系, 合肥 230026
  • 收稿日期:2011-12-05 修回日期:2012-01-31 发布日期:2012-03-21
  • 通讯作者: 张立敏 E-mail:mzha@ustc.edu.cn
  • 基金资助:

    国家自然科学基金(21073177)资助项目

Photodissociation Spectra of OCS+ via A2ПX2П Transitions

ZHOU Dan-Na, CHEN Lin, WU Dan, ZHANG Li-Min   

  1. Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, P. R. China
  • Received:2011-12-05 Revised:2012-01-31 Published:2012-03-21
  • Contact: ZHANG Li-Min E-mail:mzha@ustc.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21073177).

摘要: 在超声分子束条件下, 由423、420、412.2和408.4 nm的电离激光使OCS分子通过[3+1]共振增强多光子电离(REMPI)制备出OCS+ (X2Π)离子后, 在260-325 nm范围内扫描解离激光获得了OCS+离子经由A2Π3/2X2Π3/2 (000)和A2Π1/2X2Π1/2 (000, 001)跃迁的分质量光解离谱(母体离子OCS+的凹陷谱和碎片离子S+的增强谱). 其中A2Π1/2X2Π1/2 (001)跃迁的光解离谱是首次观察到. 由A2Π3/2X2Π3/2 (000)光解离谱得到了A2Π3/2电子态的光谱常数T0=31411.3 cm-1, ν1=814.3 cm-1; 由A2Π1/2X2Π1/2 (000)光解离谱得到了A2Π1/2电子态的光谱常数ν1=816 cm-1, ν2=(380.4±2.8) cm-1, ν3=(2052.7±5.1) cm-1, 而从A2Π1/2X2Π1/2 (001)光解离谱拟合出的A2Π1/2电子态的ν1 (786.4 cm-1)稍有不同, 表明在A2Π1/2X2Π1/2 (001)跃迁中X2П1/2电子态的C-O键振动(ν3)激发影响了A2Π1/2电子态C-S键的振动(ν1). 实验结果表明: 在A2Π1/2X2Π1/2 (000, 001)跃迁的光解离谱中能够显著观察到属于A2Π电子态的ν2弯曲振动模激发的谱峰, 例如A2Π1/2 (020, 120, 021, …), 而在A2П3/21υ2υ3)←X2Π3/2(000)跃迁的光解离谱中几乎没有观察到属于ν2弯曲振动模激发的谱峰. 这种弯曲振动激发和A2П电子态的旋轨分裂分量(Ω)的相关性可以通过A2Π电子态的Fermi共振和Renner-Teller 效应来解释.

关键词: OCS+, 光解离, 弯曲振动模激发, 光碎片激发谱

Abstract: In the wavelength range 260-325 nm, we obtained mass-resolved dissociation spectra of OCS+ via A2П3/2X2П3/2 (000) and A2П1/2X2П1/2 (000, 001) transitions by preparing OCS+ (X2П) ions via [3+1] resonance enhanced multiphoton ionization (REMPI) of OCS molecules at 423, 420, 412.2, and 408.4 nm. The mass-resolved dissociation spectra of OCS+ via A2П1/2X2П1/2 (001) were observed for the first time. The spectroscopic constants T0=31411.3 cm-1 and v1=814.3 cm-1 for the OCS+ (A2П3/2) state were deduced from the A2П3/2X2П3/2 (000) photodissociation spectra, and the spectroscopic constants v1=816 cm-1, v2=(380.4± 2.8) cm-1, and v3=(2052.7±5.1) cm-1 for the OCS+ (A2П1/2) state were deduced from the A2П1/2X2П1/2 (000) spectra. The spectroscopic constant v1=786.4 cm-1 was deduced from the A2П1/2X2П1/2 (001) photodissociation spectra. The results show that the C-O stretching mode excitation of X2П1/2 can affect the C-S stretching mode vibration of the A2П1/2 state via A2П1/2X2П1/2 (001) transitions. Bands involving the bending v2 mode excitation of A2П, such as A2П1/2 (020, 120, 021, …), were observed for the A2П1/2X2П1/2 (000, 001) transitions, but were not observed for the A2П3/21υ2υ3) ←X2П3/2 (000) transitions in the photodissociation spectra. The reason for this dependence of the bending v2 mode excitation of A2П on the spin-orbit splitting of the 2П state can be attributed to the Fermi resonance and Renner-Teller effect of OCS+ (A2П).

Key words: OCS+, Photodissociation, Bending mode excitation, Photofragment excitation spectrum

MSC2000: 

  • O649