Multiphoton Ionization of Potassium Atoms in Femtosecond Laser Fields
Wankai Li , Yue Lei , Xing Li , Tao Yang , Mei Du , Ying Jiang , Jialong Li , Sizuo Luo , Aihua Liu , Lanhai He , Pan Ma , Dongdong Zhang*, and Dajun Ding*
Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
Abstract：We study the multiphoton ionization of potassium atoms in 800 nm and 400 nm femtosecond laser fields. In the 800 nm laser field, the potassium atom absorbs three photons and emits one electron via one photon resonance with the $4p$ intermediate state with the help of the ac-Stark shift. The resonance feature is clearly shown as an Autler–Townes (AT) splitting and is mapped out in the electron kinetic energy spectrum. In a 400 nm laser field, although one photon resonance is possible with the $5p$ state, no splitting is observed. The different transition amplitudes between $4s$–$4p$ and $4s$–$5p$ explain the observed results. Due to the AT effect, an unexpected peak in the photoelectron energy spectrum that violates the dipole transition rule is observed. A preliminary explanation involving the spin-orbit interaction in the $p$ state is given to account for this component. The observed AT-splitting in the electron kinetic energy distribution can be used as an effective method to calibrate the intensity of a laser field.
收稿日期: 2021-02-23
出版日期: 2021-05-02
引用本文:
. [J]. 中国物理快报, 2021, 38(5): 53202-.
Wankai Li , Yue Lei , Xing Li , Tao Yang , Mei Du , Ying Jiang , Jialong Li , Sizuo Luo , Aihua Liu , Lanhai He , Pan Ma , Dongdong Zhang, and Dajun Ding. Multiphoton Ionization of Potassium Atoms in Femtosecond Laser Fields. Chin. Phys. Lett., 2021, 38(5): 53202-.
2021, Vol. 38 
