Signatures of tunneling and multiphoton ionization in the electron-momentum distributions of atoms by intense few-cycle laser pulses

M. WICKENHAUSER, X.M. TONG, D.G. ARBÓ, J. BURGDÖRFER, AND C.D. LIN

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

The American Physical Society

Lugar: New York; Año: 2006 vol. 74 p. 41402 - 41402

1050-2947

  Electron-momentum distributions for above-threshold ionization of argon in a few-cycle, linearly polarized laser pulse are investigated. Spectral features characteristic of multiphoton as well as tunneling ionization coexist over a range of the Keldysh parameter in the transition regime ~1. Surprisingly, the simple strong-field approximation (SFA) is capable of reproducing the key features of the two-dimensional momentum distributions found in the full solution of the time-dependent Schrödinger equation, despite the fact that SFA is known to severely underestimate the total ionization probability.