This research utilizes the Electron Shelving (ES) technique to obtain a lifetime measurement of the 3P1 energy state of strontium. The 5s21 S0 → 5p 3 P1 intercombination transition is important because of its promising usefulness in optical frequency standards and high resolution spectroscopy. Unfortunately, the transition lacks a high photon scattering rate to produce a significant signal for optical studies and therefore it is advantageous to monitor the vastly stronger 1S 0 →1 P1 transition. This lifetime measurement yielded a value of tau = 23 +/- 3 mus (systematic uncertainty), which is longer than other current experimental values established in literature. Additional lineshape studies with a dependence on magnetic fields, gravitational acceleration, and laser power were performed and are discussed briefly. These lineshape studies allow an upper linewidth limit to be placed on the pumping laser causing this transition, making these secondary studies a useful method to characterize the laser.

An experiment studying the effects of photoassociation in a quantum degenerate gas of 7Li bosons has been performed in a permanent magnet trap. A saturation in the one-photon photoassociation rate and a shift in the resonance due to the applied light field from the 2S 1/2 ground state to the 2P1/2 v ' = 83 excited molecular vibrational state have been measured and compared with theory. Limitations in the ability of the permanent magnet apparatus to study photoassociation in a Bose-Einstein condensate have prompted the development of a magneto-optical trap and an electro-magnetic trap. These new traps will assist in the process of creating a large BEC where the effects of photoassociation will be studied.

The ionization of potassium np Rydberg atoms with $n\sim388$ by pulsed unidirectional electric fields, termed half-cycle pulses (HCPs), with various well-characterized shapes (rectangular, triangular, and sawtooth) and durations $T\sb{p}$ comparable to the classical electron orbital period $T\sb{n}$ is investigated. The experimental results are compared to classical trajectory Monte Carlo (CTMC) simulations and the classically-scaled results of quantum calculations undertaken at $n=5.$ The data show that in the intermediate regime, $T\sb{p}\sim T\sb{n},$ the threshold field for ionization becomes sensitive to the shape and rise time of the HCP, increasing with increasing rise time. For each pulse shape, the agreement between the experimental measurements and both the CTMC and quantum calculations is very good.

A dual species electromagnetic trap has been developed for the purpose of studying quantum degeneracy and the BCS phase transition in 6Li. Since the symmetry requirements of quantum mechanics forbid collisions between identical ultra-cold fermions, the standard method of cooling atoms in a magnetic trap, evaporative cooling, will not work. To circumvent this obstacle we evaporatively cool 7Li, the boson, and allow sympathetic collisions between the bosons and fermions to cool the 6Li to quantum degeneracy. This thesis will cover the experimental details pertaining to capturing, cooling, and probing a mixture of atomic 7Li and 6Li.

Bose-Einstein condensation (BEC) of 7Li has been investigated. Because the effective interaction between 7Li atoms is attractive, the condensate occupation number N 0 is limited to ∼ 1250 atoms, and when this limit is exceeded, the condensate becomes unstable with respect to mechanical collapse. The interplay of this limit and the natural growth of the condensate during BEC leads to complicated dynamical behavior, which has been studied both theoretically and experimentally. It has been modeled by solving the quantum Boltzmann equation, in conjunction with results from the nonlinear Schrodinger equation. It is found that N0 oscillates rapidly as the condensate alternately fills and collapses, and that the oscillations can persist for many cycles before the gas comes to equilibrium. Experimental evidence for these oscillations was obtained by repeatedly producing a condensate and measuring N 0. The results were seen to vary randomly from one measurement to the next, which is to be expected as the timing of the oscillations is intrinsically stochastic. The distribution of N0 values occurring was measured, and provides quantitative information on the condensate growth and collapse. The equilibration process itself was also observed, by quenching the gas into degeneracy and observing its relaxation. In order to carry out these experiments, sensitive measurement and analysis techniques were developed which enabled N0 to be determined in situ with an accuracy of +/-20% and a precision of +/-60 atoms. The theoretical tools used to study quantum degenerate gases were also applied to the important experimental technique of evaporative cooling, which led to substantial optimization and improvements. As part of this study, the rate constant for dipolar relaxation was measured to be 1.05 +/- 0.1 x 10-14 cm3/s, in agreement with theoretical predictions.

We investigate the interaction of a xenon Rydberg atom with a metallic surface in an electric field. We also present a Stark map for xenon Rydberg atoms. The xenon Rydberg atom is modeled using a pseudopotential fitted to experimentally obtained quantum defects. We show that several xenon levels exhibit avoided crossings with the application of a DC electric field. Additional avoided crossings occur as the xenon Rydberg atom approaches a surface. These avoided crossings lead to mixing between levels of different principal quantum number n. Nonadiabatic transition through these avoided crossings can explain recent results involving ionization of state-selected xenon Rydberg atoms near a metal surface.

The resonant ionization of Xe(nf) Rydberg atoms in extreme red and blue Stark states at a conducting surface is investigated. The Xe( nf) Rydberg atoms are created by laser induced photoexcitation of xenon 6s'[1/ 2]0 metastable atoms created within a DC discharge. Following ionization the resulting Rydberg ion core is attracted to the surface by its image charge where it will be neutralized. To prevent this, an electric field is applied perpendicular to the surface. The critical field required to observe the ions provides a measure of the atom/surface separation at which resonant ionization occurred. The data show that the extreme members of a given Stark manifold ionize at similar atom/surface separations pointing to strong perturbations in the energies and structure of the atomic states induced by the presence of the surface.

The characteristics of strongly-polarized quasi-one-dimensional (quasi-1D) Rydberg atoms produced by photoexcitation of selected Stark states in the n = 350 Stark manifold are investigated by studying their ionization when subject to sub-nanosecond unidirectional electric field pulses, termed half-cycle pulses (HCPs), directed both parallel and perpendicular to the atomic axis. The observed differences in the ionization characteristics provide a measure of the anisotropy of the momentum distribution and thus of the quasi-1D nature of the states. The response of such states to a train of HCPs directed parallel and anti-parallel to the axis of polarization of the initial state is also investigated. Pronounced differences in the survival probability are observed confirming theoretical predictions that the dynamical response of the system will be very different for these two conditions. The presence of noise is also observed to play a crucial role in the dynamics. Reasonable agreement between experiment and theory is achieved.

The response of potassium Rydberg atoms with principal quantum number, $n \ge 400$, to fast, unidirectional electric field pulses, termed half-cycle pulses (HCPs), is investigated experimentally and the results compared to classical trajectory Monte Carlo calculations. The durations, $T\sb{p}$, of the HCPs span the transition from the short pulse regime, where the classical orbital period of the initial state $T\sb{n} >> T\sb{p}$, to the long pulse regime, where $T\sb{p}z >> T\sb{n}$. In experiments with single HCPs, ionization probabilities measured as a function of pulse width and amplitude agree with theory on an absolute scale without any adjustable parameters, providing a benchmark test for the validity of the classical limit of ionization. HCPs are also used to create and probe very high-n Rydberg wavepackets. Application of a HCP with $T\sb{p} > T\sb{n}$ leads to population of a coherent superposition of Stark states. In each case, the time-evolution of the wavepacket is examined by applying a second short HCP after a variable time delay. This probe pulse ionizes a fraction of the atoms present and the survival probability exhibits pronounced oscillations that are well reproduced by CTMC simulations. The CTMC calculations show that the observed quantum beats reflect the time-evolution of the distribution of the z component, $p\sb{z}$, of the momentum of the excited electron. The first experimental studies of excitation and ionization by a sequence of short HCPs are also reported. Application of a sequence of identical pulses results in a multi-step excitation followed by ionization. The ionization probability of atoms with $n\sb{i}\sim 388$ subject to a sequence of identical, equally-spaced 2 ns HCPs were measured as a function of HCP height and pulse repetition frequency, $\omega\sb{p}$. The experimental data show that the Rydberg atoms are considerably more stable against ionization when the frequency of the perturbation scaled to the orbital frequency of the initial state, $\omega\sb0$ = $n\sbsp{i}{3}\omega\sb{p}$, is $\omega\sb0 \sbsp{\sim}{>} 1$ than when $\omega\sb0 << 1$. This stability is not as pronounced in a CTMC calculation that uses $\delta$-function impulses.

This thesis details the optical development of an ion/electron accelerating facility at Southwest Research Institute which is currently being used to calibrate the Plasma Spectrometer for the Cassini Mission to Saturn. The optical development involves particle (ion) ray tracing of each element in the facility in order to computationally determine the focusing and mass separating parameters of each of the elements. This computational data is then compared with the actual output beam from the accelerating facility. The behavior of each of the elements is determined and its affect on the output beam is established. Changes to the design of the facility can then be made based upon this information.