Enhanced nonlinear double excitation of He in intense extreme ultraviolet laser fields |
| |
Authors: | Hishikawa A Fushitani M Hikosaka Y Matsuda A Liu C-N Morishita T Shigemasa E Nagasono M Tono K Togashi T Ohashi H Kimura H Senba Y Yabashi M Ishikawa T |
| |
Institution: | Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan. hishi@chem.nagoya-u.ac.jp |
| |
Abstract: | Nonlinear, three-photon double excitation of He in intense extreme ultraviolet free-electron laser fields (~24.1 eV, ~5 TW/cm2) is presented. Resonances to the doubly excited states converging to the He+ N=3 level are revealed by the shot-by-shot photoelectron spectroscopy and identified by theoretical calculations based on the time-dependent Schr?dinger equation for the two-electron atom under a laser field. It is shown that the three-photon double excitation is enhanced by intermediate Rydberg states below the first ionization threshold, giving a greater contribution to the photoionization yields than the two-photon process by more than 1 order of magnitude. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|