Ngoko Djiokap J M, Manakov N L, Meremianin A V, Hu S X, Madsen L B, Starace Anthony F
Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588-0299, USA.
Department of Physics, Voronezh State University, Voronezh 394006, Russia.
Phys Rev Lett. 2014 Nov 28;113(22):223002. doi: 10.1103/PhysRevLett.113.223002. Epub 2014 Nov 26.
Control of double ionization of He by means of the polarization and carrier-envelope phase (CEP) of an intense, few-cycle extreme ultraviolet (XUV) pulse is demonstrated numerically by solving the six-dimensional two-electron, time-dependent Schrödinger equation for He interacting with an elliptically polarized XUV pulse. Guided by perturbation theory (PT), we predict the existence of a nonlinear dichroic effect (∝I^{3/2}) that is sensitive to the CEP, ellipticity, peak intensity I, and temporal duration of the pulse. This dichroic effect (i.e., the difference of the two-electron angular distributions for opposite helicities of the ionizing XUV pulse) originates from interference of first- and second-order PT amplitudes, allowing one to probe and control S- and D-wave channels of the two-electron continuum. We show that the back-to-back in-plane geometry with unequal energy sharing is an ideal one for observing this dichroic effect that occurs only for an elliptically polarized, few-cycle attosecond pulse.
通过求解与椭圆偏振极紫外（XUV）脉冲相互作用的氦原子的六维两电子含时薛定谔方程，对利用强的、少周期极紫外（XUV）脉冲的偏振和载波包络相位（CEP）来控制氦原子的双电离进行了数值演示。在微扰理论（PT）的指导下，我们预测存在一种对CEP、椭圆率、峰值强度I和脉冲的时间持续敏感的非线性二向色性效应（∝I^{3/2}）。这种二向色性效应（即电离XUV脉冲相反螺旋度的两电子角分布的差异）源于一阶和二阶PT振幅的干涉，从而能够探测和控制两电子连续态的S波和D波通道。我们表明，具有不等能量分配的背对背面内几何结构是观察这种仅发生在椭圆偏振、少周期阿秒脉冲的二向色性效应的理想结构。
