The ultraviolet (UV)-induced dissociation and photofragmentation of gas-phase CH₂BrI molecules induced by intense femtosecond extreme ultraviolet (XUV) pulses at three different photon energies are studied by multi-mass ion imaging. Using a UV-pump–XUV-probe scheme, charge transfer between highly charged iodine ions and neutral CH₂Br radicals produced by C–I bond cleavage is investigated. In earlier charge-transfer studies, the center of mass of the molecules was located along the axis of the bond cleaved by the pump pulse. In the present case of CH₂BrI, this is not the case, thus inducing a rotation of the fragment. We discuss the influence of the rotation on the charge transfer process using a classical over-the-barrier model. Our modeling suggests that, despite the fact that the dissociation is slower due to the rotational excitation, the critical interatomic distance for charge transfer is reached faster. Furthermore, we suggest that charge transfer during molecular fragmentation may be modulated in a complex way.

中文翻译：

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强飞秒 XUV 脉冲探测的 CH2BrI 的紫外线诱导解离

通过多质量离子成像研究了在三种不同光子能量下由强飞秒极紫外 (XUV) 脉冲诱导的气相 CH ₂ BrI分子的紫外 (UV) 诱导解离和光致碎裂。使用 UV 泵-XUV 探针方案，研究了高电荷碘离子与 C-I 键断裂产生的中性 CH _{2 Br 自由基之间的电荷转移。}在早期的电荷转移研究中，分子的质心位于泵浦脉冲切割的键轴上。_{在目前的 CH 2}案例中BrI，情况并非如此，因此引起了片段的旋转。我们使用经典的越障模型讨论了旋转对电荷转移过程的影响。我们的模型表明，尽管由于旋转激发，解离速度较慢，但​​可以更快地达到电荷转移的临界原子间距离。此外，我们认为分子分裂过程中的电荷转移可以以复杂的方式进行调节。