Dissociation and ionization dynamics of CF3I and CH3I molecules via pump-and-probe experiments using soft x-ray free-electron laser
Dissociation and ionization dynamics of CF3I and CH3I molecules via pump-and-probe experiments using soft x-ray free-electron laser
复制标题
DOI：
10.1088/1361-6455/abcd20
复制
发表时间：
2020-11
期刊：
影响因子：
--
通讯作者：
T. Gejo;T. Nishie;T. Nagayasu;K. Tanaka;Y. Tanaka;A. Niozu;K. Nagaya;R. Yamamura;N. Futamata;T. Suenaga;O. Takahashi;T. Togashi;S. Owada;H. Fujise;A. Verna;M. Yabashi;M. Oura
中科院分区：
文献类型：
--
作者：
T. Gejo;T. Nishie;T. Nagayasu;K. Tanaka;Y. Tanaka;A. Niozu;K. Nagaya;R. Yamamura;N. Futamata;T. Suenaga;O. Takahashi;T. Togashi;S. Owada;H. Fujise;A. Verna;M. Yabashi;M. Oura
CF 3 I和CH 3 I分子的解离和电离动力学研究使用泵浦和探测技术，采用软X射线自由电子激光器（SACLA）在日本。首先，时间分辨内壳层光电子能谱被用来观察CF 3 I的超快反应，通过监测碘的4d电子。发现在光电子谱中观察到的I4 d态的变化发生在泵浦激光脉冲后的约40 fs的上升时间τ，这比采用超快气相电子衍射技术时观察到的变化快。这意味着内壳层光电子能谱对Franck-Condon区附近的势面更敏感。其次，266 nm的强激光强度（相当于1.9 × 1014 W cm−2的功率密度）可以通过多光子电离过程轻松地将CH 3 I分子电离，并且价光电子谱的时间依赖性清楚地表明，在皮秒时间尺度下，由于产生大量离子的空间电荷效应，泵浦激光脉冲导致光谱峰移动。因此，SACLA不仅可以用来研究分子解离的动力学过程，而且可以通过光电子能谱峰的移动来研究电离过程。
The dissociation and ionization dynamics of CF3I and CH3I molecules were investigated using a pump-and-probe technique that employs a soft x-ray free-electron laser (SACLA) in Japan. First, time-resolved inner-shell photoelectron spectroscopy was employed to observe the ultrafast reaction of CF3I by monitoring iodine 4d electrons. The change in the I 4d state observed in the photoelectron spectra is found to occur with a rise time τ of approximately 40 fs after a pump laser pulse, which is faster than that observed when an ultrafast gas-phase electron diffraction technique is employed. This implies that the inner-shell photoelectron spectroscopy is more sensitive to the potential surface near the Franck–Condon region. Second, a strong laser intensity at 266 nm, corresponding to a power density of 1.9 × 1014 W cm−2, can easily ionize CH3I molecules via multiphoton ionization processes, and the time dependence of the valence photoelectron spectra clearly shows that at the picosecond timescale, this pump laser pulse causes spectral peaks to shift owing to space-charge effects in response to the large amount of ions generated. Thus, the SACLA can be a useful tool to investigate not only the dynamical process of molecular dissociation but also the ionization process through the shift in the peaks of photoelectron spectra.