Multiphoton electron detachment by a superposition of static and ac   filds
  A theory of electron detachment from atoms or negative ions by a superposition of a static and a laser (or, more generally, ac) fields, parallel to each other, is developed in the case when the photon energy and the field amplitude are much less than the detachment energy and intra-ion field, respectively. Simple analytical results together with their validity conditions are obtained. Several qualitatively different regimes of detachment have been identified. Applications of the present theory to electron emission from metal and semiconductor surfaces and from photosynthetic bio-complexes are discussed. 
A. G. Kofman and G. P. Berman
physics.atom-ph quant-ph