An alternative approach to condensed-phase photoionization

Starting from Maxwell's equations for the electromagnetic field in a linear Kramers-Kronig dielectric, a general expression for photoionization cross sections of atoms or molecules embedded in a medium and a dielectric influence function (DIF) are derived in this Letter firstly. It is also suggested that a density turning point (DTP) of a photoionization process may be viewed as the critical density N-c(omega) where the photoionization properties may have notable and different variations with density. (c) 2005 Elsevier B.V. All rights reserved.