It is commonly accepted in the strong-laser physics community that the dynamical regime of atomic ionization is characterized by the Keldysh parameter γ . Two distinct cases, where γ < 1 and γ > 1, are associated with ionization mechanisms that are predominantly in the tunneling and in the multiphoton regimes, respectively. We perform fully three-dimensional quantum simulations for the ionizati...

Title of Document: STUDY OF THE FEMTOSECOND DYNAMICS AND SPECTROSCOPY OF LASER IONIZED PLASMAS. JJennifer Anne Elle, Doctor of Philosophy, 2015 Directed By: Professor Howard Milchberg Department of Physics Ultra-short laser pulses are used to ionize gas in different configurations and study the plasma and ionization dynamics. The variation in non-linear index of refraction as a function of time...

Sub-micrometer-sized targets are found in intense laser–cluster interaction experiments and laser-based material processing. Here, we investigate the internal field localization due to Mie scattering its effect on ionization dynamics sub-micrometer-sized clusters using calculation particle-in-cell simulations. As a result of intertwined processes pulse propagation ionization, sub-micrometer nan...

The interaction of Li– with an ultrashort intense laser pulse is investigated by solving the time-dependent Schrödinger equation (TDSE) in the dipole approximation using a two-active electron approach. We describe the numerical solution of the TDSE and give a more detailed presentation of a technique for obtaining angular distributions for double ionization by intense ultrashort laser pulses. W...

Neutral atoms and clusters desorbed from a solid germanium surface by ion bombardment are detected by laser postionization and time-of-flight mass spectrometry. Two different photoionization schemes are compared which are generally believed to be candidates for the 'soft' ionization of polyatomic species without significant photon induced fragmentation. First, a single photon ionization process...

Beam-driven plasma wakefield acceleration using low-ionization-threshold gas such as Li is combined with laser-controlled electron injection via ionization of high-ionization-threshold gas such as He. The He electrons are released with low transverse momentum in the focus of the copropagating, nonrelativistic-intensity laser pulse directly inside the accelerating or focusing phase of the Li blo...

We studied the ionization probability of Na atoms in an intense Ti–sapphire laser at 800 nm versus the laser pulse duration. The ionization probabilities for the Na(3s) and Na(3p) states were found to vary non-monotonically with the pulse duration at a constant peak laser intensity. The abnormal (non-monotonic) pulse duration dependence was traced to the competition between resonant and non-res...

One of the most striking surprises of recent years in intense laser-matter interactions has come from multiple ionization by intense short laser pulses: Correlated (nonsequential) double ionization rates were found to be several orders of magnitude higher than the uncorrelated sequential mechanism allows. This discrepancy has made the characteristic “knee” shape in the double ionization yield v...

A two-dimensional model atom is employed to study the ionization behavior of initially excited atomic states in highly-frequent intense laser pulses beyond the dipole approximation. An additional regime of ionization suppression is found at laser intensities where the stabilization effect is expected to break down. The appearance of this effect is due to a strong coupling of the initial wave fu...