Reconstruction of Atomic Ionization Probabilities in Intense Laser   Fields
  Application of a parallel-projection inversion technique to z-scan spectra of multiply charged xenon and krypton ions, obtained by non-resonant field ionization of neutral targets, has for the first time permitted the direct observation of intensity-dependent ionization probabilities. These ionization efficiency curves have highlighted the presence of structure in the tunnelling regime, previously unobserved under full-volume techniques. 
T. R. J. Goodworth, W. A. Bryan, I. D. Williams and W. R. Newell