“Laser cooling and trapping, femtosecond light creation, and coincident electron and ion momentum imaging was combined in a world-wide unique experimental setup. These state-of-the-art techniques were used to control atomic systems and analyze the few-body quantum dynamics in multi-photon ionization of lithium. An all-optical, near-resonant laser atom trap (AOT) was developed to prepare a lithium gas at milli-Kelvin temperatures. The atoms can be resonantly excited to the state 22 P3/2(ml = +1) with a high degree of polarization and are used as a target to study atomic multi-photon ionization in the field of an intense laser source based on an optical parametric chirped pulse amplifier (OPCPA) that provides few femtosecond laser pulses with intensities of up to 1012W/cm2. The momenta of emitted electrons and Li+ ions are analyzed in a COLTRIMS spectrometer with excellent resolution. The fundamental scientific questions addressed with this setup relate to the initial state dependence of multi-photon ionization processes. The influence of relative polarizations of target and laser pulse was studied in the most fundamental conceivable chiral systems. We studied a symmetry breaking between left- and right-handed circular laser polarization, so-called circular dichroism, in the ionization of the 22 P3/2(ml = +1). It was found that the polarization-dependent dressing of the atoms in the field causes significant Autler-Townes shifts resulting in a strong circular dichroism that affects not only the total ionization rate and the photo-electron angular distributions (PAD) but also the energy of the emitted photons. The measured energy spectra, PADs, and momentum distributions are in excellent agreement with a theoretical model solving the time-dependent Schrödinger equation in the single-active electron approximation”--Abstract, page iii.
Schulz, Michael, 1959-
Madison, Don H.
Samaranayake, V. A.
Ph. D. in Physics
National Science Foundation (U.S.)
Missouri University of Science and Technology
xi, 74 pages
© 2020 Aruma Handi Nishshanka Chandrajith De Silva, All rights reserved.
Dissertation - Open Access
Electronic OCLC #
De Silva, Aruma Handi Nishshanka Chandrajith, "Symmetry-breaking in the multi-photon ionization dynamics of oriented atoms" (2020). Doctoral Dissertations. 2911.