CS_2^+_g^2的(1+1)光解离动力学研究

Photodissociation of CS_2^+(~2∏_g) via (1+1) Excitation

在气束条件下 ,利用 4 83.2nm的激光 (3+ 1)共振增强多光子电离 (REMPI)CS2 分子以产生CS2 +离子源 ,用另一束可调谐激光在 4 2 4～ 4 82nm内 ,通过对CS2 +( X2 Πg) (1+ 1)双光子共振解离产生的碎片离子激发谱的探测 ,来获取CS2 +的光解离动力学信息。光解离碎片S+的激发谱(PHOFEX)可归属为CS2 +( A2 Πu,3/2 (v′ =0～ 4 ,v′ =v1′ + (1/ 2 )v2 ′)← X2 Πg ,3/2 (0 ,0 ,0 ) )和 ( A2 Πu,1/2 (v′ =0～ 4 )← X2 Πg ,1/2 (0 ,0 ,0 ) )的跃迁。对CS2 +光解离动力学的研究表明 ,其产生S+的通道为 :(i)CS2 +吸收一个光子从基态 X2 Πg 共振激发至 A2 Πu 态 ,(ii)已布居的 A2 Πu 态的振动能级和 X2 Πg 态的高振动能级产生耦合 ,(iii)吸收第二个光子从上述耦合的振动能级进一步激发至 B2 Σu+态 ,再通过 B2 Σu+态与4 Σ- 态间的自旋 -轨道相互作用 ,经由4 Σ- 排斥态解离产生S++CS。

Photodissociation dynamics of CS 2 + molecular ions has been investigated by (1+1) two photon resonance technique. CS 2 + were prepared by (3+1) resonance enhanced multi photon ionization(REMPI) of CS 2 molecules at 483.2nm. The photofragment S + excitation(PHOFEX) spectra were recorded by scanning another laser in the 424~482nm region, and were assigned essentially to CS 2 +( 2Π u,3/2 ( v ′=0~4)← 2Π g,3/2 (0,0,0)) and ( 2Π u,1/2 ( v ′=0~4)← 2Π g,1/2 (0,0,0)) (here v′=v 1′+(1/2)v 2′ ) transitions. The S + production channel was preliminarily attributed to, (i) one-photon excitation CS 2 + from the ground state 2Π g to the excited state 2Π u; (ii) vibronic coupling between the 2Π u state and the high vibrational levels in the 2Π g state; (iii) second photon excitation from the coupling vibrational levels to the excited state 2Σ u + and dissociation to produce S ++ CS via the repulsive 4Σ - state through spin-orbit interaction between the 2Σ u + and 4Σ - states.