Mabbs Richard, Pichugin Kostyantyn, Surber Eric, Sanov Andrei
Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA.
J Chem Phys. 2004 Jul 1;121(1):265-72. doi: 10.1063/1.1756869.
The evolution of the I(-) channel in I(2)Br(-) photodissociation is examined using time-resolved negative-ion photoelectron imaging spectroscopy. The 388 nm photodetachment images obtained at variable delays following 388 nm excitation reveal the transformation of the excess electron from that belonging to an excited trihalide anion to that occupying an atomic orbital localized on the I(-) fragment. With increasing pump-probe delay, the corresponding photoelectron band narrows on a approximately 300 fs time scale. This trend is attributed to the localization of the excess-electron wave function on the atomic-anion fragment and the establishment of the fragment's electronic identity. The corresponding band position drifts towards larger electron kinetic energies on a significantly longer, approximately 1 ps, time scale. The gradual spectral shift is attributed to exit-channel interactions affecting the photodetachment energetics, as well as the photoelectron anisotropy. The time-resolved angular distributions are analyzed and found consistent with the formation of the asymptotic I(-) fragment.
利用时间分辨负离子光电子成像光谱研究了I⁻通道在I₂Br⁻光解离过程中的演化。在388 nm激发后不同延迟时间获得的388 nm光剥离图像揭示了多余电子从属于激发态三卤化物阴离子的电子转变为占据I⁻碎片上局域化原子轨道的电子。随着泵浦 - 探测延迟增加，相应的光电子能带在约300 fs的时间尺度上变窄。这种趋势归因于多余电子波函数在原子阴离子碎片上的局域化以及碎片电子身份的建立。相应的能带位置在明显更长的约1 ps时间尺度上向更大的电子动能漂移。这种逐渐的光谱移动归因于影响光剥离能量学以及光电子各向异性的出射通道相互作用。对时间分辨角分布进行了分析，发现与渐近I⁻碎片的形成一致。
