Laser ionization of noble gases by Coulomb-barrier suppression

TLDR

Ionization occurs exclusively in the tunneling regime. The study aimed to compare experimental ion production rates with predictions from several theoretical models. The authors used a 1.053‑μm, 1‑psec Nd:glass laser to ionize noble gases and compared the resulting ion production rates with multiple theoretical predictions. A systematic intensity scan from 10^13 to 10^16 W/cm² produced charge states up to Xe12+, and the experimental ion‑production curves matched well with both an extended Keldysh tunneling model and a primitive Coulomb‑barrier suppression model, suggesting that barrier‑suppression ionization dominates at this wavelength and intensity range. Reference: Sov.

Abstract

Laser ionization of noble gases was studied with a 1.053-μm, 1-psec Nd:glass laser. A systematic scan of intensities from mid-1013 W/cm2 to mid-1016 W/cm2 was performed, resulting in the production of charge states as high as Xe12+. Ionization occurs exclusively in the tunneling regime. We compare experimental ion production rates with those predicted by several different theories. Agreement between experimental ion-production curves and theoretical predictions is good for two theoretical models: (1) an elaboration of the Keldysh tunneling model, developed by Ammosov et al. [ Sov. Phys. JETP64, 1191 ( 1986)] and (2) a much more primitive model, based on Coulomb-barrier suppression, in which tunneling and other quantum-mechanical effects are ignored completely. The success of the more primitive model suggests that a new term, barrier-suppression ionization, rather than tunneling or multiphoton ionization, may be the most appropriate at this wavelength and in this range of intensities.