Laser-induced non-sequential double ionization investigated at and below the threshold for electron impact ionization
Laser-induced non-sequential double ionization investigated at and below the threshold for electron impact ionization
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DOI：
10.1088/0953-4075/36/15/308
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发表时间：
2003-08
期刊：
影响因子：
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通讯作者：
E. Eremina;Xiaojun Liu;H. Rottke;W. Sandner;A. Dreischuh;F. Lindner;F. Grasbon;G. Paulus;H. Walther;R. Moshammer;B. Feuerstein;J. Ullrich
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文献类型：
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作者：
E. Eremina;Xiaojun Liu;H. Rottke;W. Sandner;A. Dreischuh;F. Lindner;F. Grasbon;G. Paulus;H. Walther;R. Moshammer;B. Feuerstein;J. Ullrich
利用关联电子-离子动量测量研究了激光诱导Ar和Ne的非顺序双电离。光强度的选择在一个政权和低于阈值，其中，在再散射模型，单电荷离子核的电子碰撞电离预计将成为大力禁止。然而，我们发现Ar 2+离子动量分布和电子-电子动量相关指示的直接碰撞电离。在准静态模型中，这可以通过假设光波的电场在散射的瞬间降低了单电荷离子核的电离势来理解。发现离子动量分布在垂直于光束偏振矢量的轴上的投影的宽度与光脉冲中的峰值电场强度的平方根成比例。在电子碰撞电离之后，从可用的相空间中不期望这样的缩放。这可能表明，散射瞬间的电场通常不为零，并决定了横向动量分布。我们的实验结果与几个理论结果的比较。
We use correlated electron–ion momentum measurements to investigate laser-induced non-sequential double ionization of Ar and Ne. Light intensities are chosen in a regime at and below the threshold where, within the rescattering model, electron impact ionization of the singly charged ion core is expected to become energetically forbidden. Yet we find Ar2+ ion momentum distributions and an electron–electron momentum correlation indicative of direct impact ionization. Within the quasistatic model this may be understood by assuming that the electric field of the light wave reduces the ionization potential of the singly charged ion core at the instant of scattering. The width of the projection of the ion momentum distribution onto an axis perpendicular to the light beam polarization vector is found to scale with the square root of the peak electric field strength in the light pulse. A scaling like this is not expected from the phase space available after electron impact ionization. It may indicate that the electric field at the instant of scattering is usually different from zero and determines the transverse momentum distribution. A comparison of our experimental results with several theoretical results is given.