Laser-induced bound-state phases in high-order harmonic generation
  We present single-molecule and macroscopic calculations showing that laser-induced Stark shifts contribute significantly to the phase of high-order harmonics from polar molecules. This is important for orbital tomography, where phases of field-free dipole matrix elements are needed in order to reconstruct molecular orbitals. We derive an analytical expression that allows the first-order Stark phase to be subtracted from experimental measurements. 
Adam Etches, Mette B. Gaarde and Lars Bojer Madsen
quant-ph physics.atom-ph