Transient vibration and product formation of photoexcited CS2 measured by time-resolved x-ray scattering
Transient vibration and product formation of photoexcited CS2 measured by time-resolved x-ray scattering
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DOI：
10.1063/5.0113079
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发表时间：
2022-10-28
影响因子：
4.4
通讯作者：
Bucksbaum, Philip H.
中科院分区：
文献类型：
--
作者：
Gabalski, Ian;Sere, Malick;Bucksbaum, Philip H.
我们用时间分辨X射线散射(Trxs)观测了光激二硫化碳(CS2)的内部运动和解离通道的细节。200 nm激光脉冲对气相CS2进行光激发，在不到1皮秒的时间内，激发出硫原子的弯曲和伸缩振荡运动，导致硫原子解离。在激发后的最初300fs内，我们观察到振动频率的显著变化以及C-S键的一些解离，导致硫原子处于D-1和P-3态。在1400fs以上，该解离主要与P-3原子的硫解离一致。这种通道分辨的解离时间测量是基于我们对时间窗解离径向速度分布的分析，该速度分布是使用Trxs数据的时间傅里叶变换进行测量的，并辅之以提取图像中线性特征的斜率的Hough变换。两个解离通道的相对强度既反映了它们的分支率，也反映了它们解离时间分布的差异。测量时间分辨的离解径向速度分布有助于解决先前光电子能谱工作提出的离解模型之间的差异。由AIP出版公司独家授权出版。
We have observed details of the internal motion and dissociation channels in photoexcited carbon disulfide (CS2) using time-resolved x-ray scattering (TRXS). Photoexcitation of gas-phase CS2 with a 200 nm laser pulse launches oscillatory bending and stretching motion, leading to dissociation of atomic sulfur in under a picosecond. During the first 300 fs following excitation, we observe significant changes in the vibrational frequency as well as some dissociation of the C-S bond, leading to atomic sulfur in the both D-1 and P-3 states. Beyond 1400 fs, the dissociation is consistent with primarily P-3 atomic sulfur dissociation. This channel-resolved measurement of the dissociation time is based on our analysis of the time-windowed dissociation radial velocity distribution, which is measured using the temporal Fourier transform of the TRXS data aided by a Hough transform that extracts the slopes of linear features in an image. The relative strength of the two dissociation channels reflects both their branching ratio and differences in the spread of their dissociation times. Measuring the time-resolved dissociation radial velocity distribution aids the resolution of discrepancies between models for dissociation proposed by prior photoelectron spectroscopy work. Published under an exclusive license by AIP Publishing.