Imaging charge transfer in iodomethane upon x-ray photoabsorption
Imaging charge transfer in iodomethane upon x-ray photoabsorption
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DOI：
10.1126/science.1253607
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发表时间：
2014-07-18
期刊：
影响因子：
56.9
通讯作者：
Rudenko, Artem
中科院分区：
文献类型：
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作者：
Erk, Benjamin;Boll, Rebecca;Rudenko, Artem
电荷转移的研究常常因为难以确定给定时间的电荷局域化而受到阻碍。在这里，我们使用超短x射线自由电子激光脉冲来成像在同步近红外(NIR)激光脉冲诱导解离过程中气相碘甲烷分子内的电荷重排动力学。内壳层光电离产生正电荷，正电荷最初定位在碘原子上。我们绘制了甲基和碘碎片之间的电子转移图，作为由近红外X射线延迟设置的原子间间隔的函数。我们在20埃的距离内观察到了电子转移的信号，并表明可以从经典的跨势垒模型中获得对其有效空间范围的真实估计。该方法适用于多种分子体系中电荷转移动力学的时空成像。
Studies of charge transfer are often hampered by difficulties in determining the charge localization at a given time. Here, we used ultrashort x-ray free-electron laser pulses to image charge rearrangement dynamics within gas-phase iodomethane molecules during dissociation induced by a synchronized near-infrared (NIR) laser pulse. Inner-shell photoionization creates positive charge, which is initially localized on the iodine atom. We map the electron transfer between the methyl and iodine fragments as a function of their interatomic separation set by the NIR-x-ray delay. We observe signatures of electron transfer for distances up to 20 angstroms and show that a realistic estimate of its effective spatial range can be obtained from a classical over-the-barrier model. The presented technique is applicable for spatiotemporal imaging of charge transfer dynamics in a wide range of molecular systems.