摘要
In this work, we mainly investigate the NH3 molecular multiphoton ionization process by using the photoelectron velocity map imaging technique. Under the condition of femtosecond laser(wavelength at 800 nm), the photoelectron images are detected. The channel switching and above-threshold ionization(ATI) effect are also confirmed. The kinetic energy spectrum(KES) and the photoelectron angular distributions(PADs) are obtained through the anti-Abel transformation from the original images, and then three ionization channels are confirmed successfully according to the Freeman resonance effect in a relatively low laser intensity region. In the excitation process, the intermediate resonance Rydberg states are C^1 A 1(6 + 2 photons process), B^1 E(6 + 2 photons process) and C^1 A 1(7 + 2 photons process), respectively. At the same time, we also find that the photoelectron angular distributions are independent of laser intensity. In addition, the electrons produced by different processes interfere with each other and they can produce a spider-like structure. We also find ac-Stark movement according to the Stark-shift-induced resonance effect when the laser intensity is relatively high.
In this work, we mainly investigate the NH3 molecular multiphoton ionization process by using the photoelectron velocity map imaging technique. Under the condition of femtosecond laser（wavelength at 800 nm）, the photoelectron images are detected. The channel switching and above-threshold ionization（ATI） effect are also confirmed. The kinetic energy spectrum（KES） and the photoelectron angular distributions（PADs） are obtained through the anti-Abel transformation from the original images, and then three ionization channels are confirmed successfully according to the Freeman resonance effect in a relatively low laser intensity region. In the excitation process, the intermediate resonance Rydberg states are C～1 A 1（6 + 2 photons process）, B～1 E（6 + 2 photons process） and C～1 A 1（7 + 2 photons process）, respectively. At the same time, we also find that the photoelectron angular distributions are independent of laser intensity. In addition, the electrons produced by different processes interfere with each other and they can produce a spider-like structure. We also find ac-Stark movement according to the Stark-shift-induced resonance effect when the laser intensity is relatively high.
作者
Le-Le Song
Ya-Nan Sun
Yan-Hui Wang
Xiao-Chun Wang
Lan-Hai He
Si-Zuo Luo
Wen-Hui Hu
Qiu-Nan Tong
Da-Jun Ding
Fu-Chun Liu
宋乐乐;孙亚楠;王艳辉;王晓春;赫兰海;罗嗣佐;胡文惠;佟秋男;丁大军;刘福春(Institute of Atomic and Molecular Physics,Jilin University,Changchun 130012,China;Jilin Institute of Chemical Technology,Changchun 132022,China;Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy,Jilin University,Changchun 130012,China;College of Electronic Science and Engineering,State Key Laboratory on Integrated Optoelectronics,Jilin University,Changchun 130012,China)
基金
Project supported by the National Natural Science Foundation of China(Grant Nos.11574116,11534004,10704028,and 11474123)
作者简介
Corresponding author:Fu-Chun Liu,E-mail:lfc@jlu.edu.cn
