Fig. 1. Schematic of experimental setup

Fig. 2. (a) Ionization photoelectron spectra of xenon atom measured under different wavelengths by experiment; (b) yield of Xe+ versus laser power at wavelength of 800 nm by experiment; (c) yield of Xe+ versus laser intensity at wavelength of 800 nm based on PPT theory

Fig. 3. Yield of Xe+ versus laser intensity under different wavelengths. (a) 800 nm; (b) 1500 nm; (c) 2000 nm

Fig. 4. Keldysh parameter γ versus laser intensity under different wavelenghts