Throughout this thesis we explore ionization processes ranging from the single photon x-ray and ultraviolet limit to the opposite adiabatic infrared limit where large numbers of photons are required for ionization. We will summarize criteria responsible for the breakdown of perturbation theory and outline key aspects of the non-perturbative theory. Our numerical calculations bridge the short wavelength limit of single photon perturbative ionization to the long wavelength limit of nonperturbative multiphoton ionization to demonstrate an optimal wavelength regime for generationof electron pulses for probing chiral systems in rare gas atoms.
Breakdown of the widely used asymptotic saddle point approximation in strong-field physics is analyzed for ionization of electrons bound to p−states. We resolve this issue by evaluating Keldysh’s ionization amplitude exactly. Finally, we present an analytic model for the perturbative two-photon ionization of atoms by arbitrary fields. As an application we reconstruct isolated attosecond pulses and pulse trains from a provided autocorrelation trace generated in a pump probe ionization measurement. The results are generalized to the non-perturbative limit.
}, year = {2023}, journal = {Department of Physics}, volume = {Ph.D}, pages = {178}, month = {2023-08}, publisher = {University of Colorado Boulder}, address = {Boulder}, }