The electric dipole moment (edm) of the ground state of cesium has been measured using optical pumping and precision polarization analyzing techniques. The measured value of $d\sb{Cs}$ = ($-$1.8 $\pm$ 6.7 $\pm$ 1.8) $\times$ 10$\sp{-24}e \ cm$ implies that the electron edm $d\sb{e}$ = ($-$1.5 $\pm$ 5.5 $\pm$ 1.5) $\times$ 10$\sp{-26}e \ cm$. This result represents more than an order of magnitude improvement over all previous limits. The basic principle of the experiment is to spin polarize cesium atoms in a cell by optical pumping (along $\vec x$) using a laser tuned to the 6$S\sb{1/2}F$ = 3 $\to$ 6$P\sb{1/2}$ transition (8944 A) in the presence of an electric field $\vec E$ along $\vec z$. The edms oriented along $\vec x$ experience a torque due to the electric field along $\vec z$ and this results in a precession of the initial polarization in the plane perpendicular to $\vec E$. The precessed polarization is detected along $\vec y$ using another laser tuned to the 6$S\sb{1/2}F$ = 4 $\to$ 6$P\sb{1/2}$(8944 A). When the electric field is reversed, the precession is in the opposite sense. The magnetic field is maintained at zero at all times except for calibration. For small angles of precession, the change in the component of the polarization along $\vec y$, denoted by $\Delta P\sb{y}$, when the electric field is reversed is given by$$\Delta P\sb{y} = 2P\sb{x}\omega\sb{E}\tau = 2P\sb{x}\left\lbrack{2d\sb{Cs}E\over (2I + 1)\hbar}\right\rbrack \tau$$ $P\sb{x}$ is the initial polarization along $\vec x$, $\omega\sb{E}$ is the precession frequency due to the electric field, $\tau$ is the characteristic decay time of the polarization and $I$ = $7\over2$ the nuclear spin of the cesium atom. A measurement of such a polarization is thus a measurement of the edm of the cesium atom and the electron edm is derived from $d\sb{Cs} = Rd\sb{e},$ where $R$ the enhancement factor is theoretically calculated to be 120.0 $\pm$ 10.0.

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Doctor of Philosophy / Department of Physics / Brett D. DePaola / In recent years, advance in ultra fast lasers and related optical technology has enhanced the ability to control the interaction between light and matter. In this dissertation, we try to improve our understanding of the interaction of atomic and molecular ladder systems with short optical pulses. A train of pulses produced by shaping the spectral phase of a single pulse from an ultra fast laser allows us to control the step-wise excitation in rubidium (Rb) atoms. As a diagnostic method, we use magneto-optical trap recoil ion momentum spectroscopy (MOTRIMS) to prepare cold target atoms and to observe atomic ions as a result of the interaction. We have explored the interactions of a finite number of optical short pulses in a train with a three-level Rb atom ladder system. Each pulse in the train is separated by a constant time interval with a fixed pulse-to-pulse phase change. In these experiments, two dimensional (2D) landscape maps show the interaction by measuring population in the uppermost state of the ladder system as a function of pulse-to-pulse time interval and phase shift. The observed structures in the 2D landscape are due to constructive or destructive interference in the interaction. Furthermore, different numbers of pulses in the train are applied to the atomic Rb three level ladder system in order to measure the effect on the interaction. The sharpness of the interference structure is enhanced by increasing the number of pulses. This phenomenon is analogous to increasing the sharpness in an optical multi-slit experiment by increasing the number of slits.

Quantum mechanics and atomic, molecular, optical (AMO) physics have been widely studied in the past century. This dissertation covers several topics in the field of AMO physics that were the focus of my Ph.D. studies, both theoretical and computational.<div><br></div><div>The first topic is related to trapping of Rydberg atoms inside an optical trap. The study focuses on the trapping energy and state mixing of Rydberg atoms based on different angular momentum state and spin-orbit coupling of the Rydberg electron. </div><div><br></div><div>The second topic is the two-electron correlations in an atom, especially double Rydberg wave packets. We have focused on the rapid autoionization and angular momentum exchanges between the double Rydberg wave packets. Then, the study of two-electron correlation is extended to the post-collision interaction (PCI) in Auger decay and a sequential ionization model. Quantum interference patterns can be found in the final correlated distributions. In the PCI study, quantum calculations and semiclassical calculations are performed to interpret the interference patterns. </div><div><br></div><div>The last topic is the ionization behavior of one-electron Rydberg atoms from a terahertz single-cycle pulse. We investigate and compare the different ionization probabilities of a Rydberg electron from an initial stationary state and a wave packet. Also, studies of the ionization behavior are extended to scaled parameters, where all physical parameters of the electron and field pulses are scaled.</div>

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M.Sc. (Instrumental Chemical Analysis) / Please refer to full text to view abstract

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Doctor of Philosophy / Department of Physics / Charles L. Cocke / The broad objective of ultrafast strong-field studies is to be able to measure and control atomic and molecular dynamics on a femtosecond timescale. This thesis work has two major themes: (1) Study of high-energy photoelectron distributions from atomic targets. (2) Electron localization control in atomic and molecular reactions using shaped laser pulses. The first section focuses on the study of photoelectron diffraction patterns of simple atomic targets to understand the target structure. We measure the full vector momentum spectra of high energy photoelectrons from atomic targets (Xe, Ar and Kr) generated by intense laser pulses. The target dependence of the angular distribution of the highest energy photoelectrons as predicted by Quantitative Rescattering Theory (QRS) is explored. More recent developments show target structure information can be retrieved from photoelectrons over a range of energies, from 4U$_p$ up to 10U$_p$, independent of the peak intensity at which the photoelectron spectra have been measured. Controlling the fragmentation pathways by manipulating the pulse shape is another major theme of ultrafast science today. In the second section we study the asymmetry of electron (and ion) emission from atoms (and molecules) by interaction with asymmetric pulses formed by the superposition of two colors (800 $\&$ 400 nm). Xe electron momentum spectra obtained as a function of the two-color phase exhibit a pronounced asymmetry. Using QRS theory we can analyze this asymmetric yield of the high energy photoelectrons to determine accurately the laser peak intensity and the absolute phase of the two-color electric field. This can be used as a standard pulse calibration method for all two-color studies. Experiments showing strong left-right asymmetry in D$^+$ ion yield from D$_2$ molecules using two-color pulses is also investigated. The asymmetry effect is found to be very ion-energy dependent.