Two-body Coulomb explosion and hydrogen migration in methanol induced by intense 7 and 21 fs laser pulses
Two-body Coulomb explosion and hydrogen migration in methanol induced by intense 7 and 21 fs laser pulses
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DOI：
10.1063/1.2768958
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发表时间：
2007-09-14
影响因子：
4.4
通讯作者：
Nakano, Hidetoshi
中科院分区：
文献类型：
--
作者：
Itakura, Ryuji;Liu, Peng;Nakano, Hidetoshi
用符合动量成像方法研究了持续时间为t=7和21fs的强激光脉冲对甲醇C-O键断裂的两体库仑爆炸。δ t=7 fs时，直接C-O键断裂途径CH3OH2+-> CH3++OH+的碎片离子反冲矢量角分布与激光偏振方向偏转30°~ 45°；在C-O键断裂之前，一个氢从碳位迁移到氧位的CH3OH2+-> CH2++H2O+的碎片离子角分布与此基本一致。当激光脉冲持续时间延长到δ t=21 fs时，直接路径和迁移路径沿激光偏振方向的角分布呈现出一个宽峰，这可能是由于激光的动态对准和/或双电离机制的改变；也就是说，从非顺序双电离到顺序双电离。然而，各向异性的迁移路径的程度小于直接路径，表明在与线偏振强激光场相互作用的甲醇解离电离过程中氢原子迁移的实质性影响。
Two-body Coulomb explosion with the C-O bond breaking of methanol induced by intense laser pulses with the duration of Delta t=7 and 21 fs is investigated by the coincidence momentum imaging method. When Delta t=7 fs, the angular distribution of recoil vectors of the fragment ions for the direct C-O bond breaking pathway, CH3OH2+-> CH3++OH+, exhibits a peak deflected from the laser polarization direction by 30 degrees-45 degrees, and the corresponding angular distribution for the migration pathway, CH2OH2+-> CH2++H2O+, in which one hydrogen migrates from the carbon site to the oxygen site prior to the C-O bond breaking, exhibits almost the same profile. When the laser pulse duration is stretched to Delta t=21 fs, the angular distributions for the direct and migration pathways exhibit a broad peak along the laser polarization direction probably due to the dynamical alignment and/or the change in the double ionization mechanism; that is, from the nonsequential double ionization to the sequential double ionization. However, the extent of the anisotropy in the migration pathway is smaller than that in the direct pathway, exhibiting a substantial effect of hydrogen atom migration in the dissociative ionization of methanol interacting with the linearly polarized intense laser field.