Real-time probing electron dynamics of an atom in a strong infrared   laser field
  We present theoretical studies on real-time probing the electron density evolution of an atom in a strong infrared (IR) laser field with few-cycle near-infrared (NIR) and attosecond extreme-ultraviolet (XUV) pulses. Our results indicate that the electron density near the tunneling barrier is reflected in the additional tunneling ionization yield with a delayed NIR pulse and the electron density near the nucleus can be probed by the single photoionization yield with a delayed XUV pulse. It turns out the NIR-probing scheme can be used to study the polarization of the system in an external IR field and the XUV-probing can be additionally applied to explore excitation dynamics during and after the IR field interaction. 
Yunpei Deng and Xinhua Xie
physics.atom-ph