Employing recent developed magneto-optical trap recoil ion momentum spectroscopy (MOTRIMS) combining cold atom, strong laser pulse, and ultrafast technologies, we study momentum distributions of the multiply ionized cold rubidium (Rb) induced by the elliptically polarized laser pulses (35 fs, $1.3 \times 10^{15}$ W/cm$^2$). The complete vector momenta of Rbn+ ions up to charge state n = 4 are recorded with extremely high resolution (0.12 a.u. for Rb$^+$). Variations of characteristic multi-bands displayed in momentum distributions, as the ellipticity varies from the linear to circular polarization, are interpreted qualitatively with the classical over-barrier ionization model. Present momentum spectroscopy of cold heavy alkali atoms presents novel strong-field phenomena beyond the noble gases.

中文翻译：

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椭圆偏振激光场中冷铷多次电离的动量光谱

利用最近开发的结合冷原子、强激光脉冲和超快技术的磁光阱反冲离子动量光谱 (MOTRIMS)，我们研究了由椭圆偏振激光脉冲 (35 fs, $1.3 \times 10^{15}$ W/cm$^2$）。以极高的分辨率（Rb$^+$ 为 0.12 au）记录了直到电荷态 n = 4 的 Rbn+ 离子的完整矢量动量。动量分布中显示的特征多带的变化，因为椭圆度从线性极化到圆极化变化，用经典的过势垒电离模型定性解释。冷重碱原子的当前动量光谱呈现出惰性气体以外的新强场现象。