Above-threshold ionization through Rydberg state population

• Published in: Physics letters. A 2017-04, Vol.381 (16), p.1405-1410
• Main Authors: Xin, Pei Pei, Yuan, Ming Hu, Wang, Han Mu, Yang, Hai Feng, Liu, Hong Ping
• Format: Article
• Language: English
• Subjects: Above-threshold ionization; Atomic core potential; Rydberg state population
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/j.physleta.2017.02.035

We present a theoretical scenario for the atomic above-threshold ionization (ATI) in an intense laser field by investigating the Rydberg state population in real time. Rather than merely viewing the final distribution of photoelectron yield directly, we monitor the Rydberg state population by projecting the time-dependent wave function onto the bound eigen-states. The calculation shows that the population of resonant Rydberg states is closely related to the peaks in photoelectron kinetic energy spectrum (PKES). For a hydrogen atom, the highest populated Rydberg states are degenerated, exactly corresponding to the first ATI peak if one additional photon is absorbed. While for non-hydrogen atoms, e.g., Ar, the highest Rydberg states are mainly populated on specific states, e.g., 3d(5s) and 4f in our case, also giving exact peak positions in PKES, where the state identification is obtained by the angular momentum resolved distribution of excited Rydberg states. This method provides an easy to understand picture for the resonance-enhanced effects in ATI as well as the role of atomic core potential in strong-field ionization. •We reveal the ionization process by monitoring the population of Rydberg states in real time.•The Raman-type coupling process of Rydberg states via the continuum is confirmed.•The role of atomic core potential in strong-field ionization is found in real time dynamics.•Forbidden transitions have been observed in non-hydrogen atom for channel couplings.