Wei Zhengrong, Li Jialin, See Soo Teck, Loh Zhi-Heng
Division of Chemistry and Biological Chemistry and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore.
Centre for Optical Fibre Technology, The Photonics Institute, Nanyang Technological University , Singapore 639798, Singapore.
J Phys Chem Lett. 2017 Dec 21;8(24):6067-6072. doi: 10.1021/acs.jpclett.7b03022. Epub 2017 Dec 5.
Studies of ultrafast molecular dynamics induced by intense laser fields can reveal new approaches to manipulating chemical reactions in the strong-field regime. Here, we show that intense few-cycle laser pulses can induce the spin-orbit state-selective C-I dissociation of the iodomethane cation (CHI) in the X̃ electronic state. Irradiation of CHI by 6 fs laser pulses with peak intensities of 1.9 × 10 W/cm followed by femtosecond extreme ultraviolet probing of the iodine 4d core-level transitions reveals dissociation of the CHI X̃ E state with a time constant of 0.76 ± 0.16 ps. By contrast, the X̃ E spin-orbit ground state does not exhibit any appreciable dissociation on the picosecond time scale. The observed spin-orbit state-selective dissociation of the X̃ state is rationalized in terms of the laser-induced coupling to the à state. Our results suggest that the intense-laser control of photodissociation channels can be potentially extended to spin-orbit split states.
对强激光场诱导的超快分子动力学的研究能够揭示在强场条件下操纵化学反应的新方法。在此，我们表明强的少周期激光脉冲能够诱导处于X̃电子态的碘甲烷阳离子（CH₃I⁺）发生自旋 - 轨道态选择性C - I解离。用峰值强度为1.9×10¹³W/cm²的6飞秒激光脉冲辐照CH₃I⁺，随后对碘的4d芯能级跃迁进行飞秒极紫外探测，结果显示CH₃I⁺的X̃²E态以0.76±0.16皮秒的时间常数发生解离。相比之下，X̃²E自旋 - 轨道基态在皮秒时间尺度上未表现出任何明显的解离现象。所观察到的X̃态的自旋 - 轨道态选择性解离可依据激光诱导与Ã态的耦合来解释。我们的结果表明，对光解离通道的强激光控制可能会潜在地扩展到自旋 - 轨道分裂态。
