Attosecond transient absorption spectroscopy:Comparative study based on three-level modeling  

作　　者：杨增强 叶地发 傅立斌 

机构地区：[1]Institute of Applied Physics and Computational Mathematics [2]CAPT, HEDPS, and IFSA Collaborative Innovation Center of Mo E, Peking University [3]Center for Fusion Energy Science and Technology, China Academy of Engineering Physics

出　　处：《Chinese Physics B》2018年第1期341-345,共5页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.11674034 and 11564033);the Foundation of President of the China Academy of Engineering Physics(Grant No.2014-1-029)

摘　　要：In the present paper, the time-resolved transient absorption spectroscopy of helium atoms is investigated based on the three-level modeling. The helium atoms are subjected to an extreme ultraviolet （XUV） attosecond pulse and a time-delayed infrared （IR） few-cycle laser field. The odd excited state are populated from the ground state by the XUV pulse due to the dipole selection rule, and probed by the time-delayed IR laser. The time-resolved transient absorption spectroscopy based on the different coupling mechanism demonstrate some different features, the photoabsorption spectrum based on three-level model with rotating wave approximation （RWA） cannot repeat the fast oscillation and the sideband structure which have been observed in the previous experimental investigation. The dressing effect of IR laser pulse on the ground state can contribute new interference structures in the photoabsorption spectrum.In the present paper, the time-resolved transient absorption spectroscopy of helium atoms is investigated based on the three-level modeling. The helium atoms are subjected to an extreme ultraviolet （XUV） attosecond pulse and a time-delayed infrared （IR） few-cycle laser field. The odd excited state are populated from the ground state by the XUV pulse due to the dipole selection rule, and probed by the time-delayed IR laser. The time-resolved transient absorption spectroscopy based on the different coupling mechanism demonstrate some different features, the photoabsorption spectrum based on three-level model with rotating wave approximation （RWA） cannot repeat the fast oscillation and the sideband structure which have been observed in the previous experimental investigation. The dressing effect of IR laser pulse on the ground state can contribute new interference structures in the photoabsorption spectrum.

关 键 词：extreme ultraviolet （XUV） PHOTOABSORPTION time delay three-level model 

分 类 号：O4[理学—物理]