Ionization Approximation theory Atomic physics Electron energy levels Helium Mathematical models Atoms Charged particles Continuum mechanics Hydrogen Ionization of gases Jost functions Laser pulses Perturbation techniques Wavefunctions Ab-initio Above-threshold ionizations Angular distributions Asymptotic stability Atomic ionization Boundary conditions Charge transfer Correlated double continuum wave function Correlation methods Coulomb potentials Coulomb waves Double photoionization Effective range theory Elasticity Electric fields