Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg, Germany. Max Planck Advanced Study Group at CFEL, 22607 Hamburg, Germany. Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany.
Center for Free-Electron Laser Science (CFEL), DESY, 22607 Hamburg, Germany.
Science. 2014 Jul 18;345(6194):288-91. doi: 10.1126/science.1253607. Epub 2014 Jul 17.
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.
电荷转移的研究常常受到确定给定时间电荷局域化的困难的阻碍。在这里，我们使用超短 X 射线自由电子激光脉冲来成像气相碘甲烷分子在同步近红外（NIR）激光脉冲诱导的离解过程中的电荷重排动力学。内壳层光致电离产生正电荷，该正电荷最初局域在碘原子上。我们通过 NIR-X 射线延迟设置的原子间分离来绘制电子在甲基和碘片段之间的转移。我们观察到电子转移的特征，其距离高达 20 埃，并表明可以从经典的过势垒模型中获得其有效空间范围的实际估计。所提出的技术适用于广泛的分子系统中电荷转移动力学的时空成像。
