非表示:
キーワード:
-
要旨:
Photoelectron emission from excited states of laser-dressed atomic helium is analyzed with respect to laser intensity-dependent excitation energy shifts and angular distributions. In the two-color exteme ultraviolet (XUV)-infrared (IR) measurement, the XUV photon energy is scanned between 20.4 eV and the ionization threshold at 24.6 eV, revealing electric dipole-forbidden transitions for a temporally overlapping IR pulse (approximate to 10(12) W cm(-2)). The interpretation of the experimental results is supported by numerically solving the timedependent Schrodinger equation in a single-active-electron approximation.