Dissociative and non-dissociative electron attachment processes are investigated via electron transfer in collisions between velocity selected Rydberg atoms and molecules. Low-energy dissociative electron attachment to BrCN and CBrCl 3, over the temperature range 300 to 450K, is examined, by measuring the velocity and angular distributions of negative ions produced. Measurements for BrCN indicate that electron capture leads to the formation of transient BrCN-* ions that dissociate with a mean lifetime tau ∼20 ps to form CN- product ions. No significant Br - production was observed over the present temperature range. Electron transfer to CBrCl3 leads to the formation of both Cl - and Br- ions. The branching ratio of the reaction pathways dramatically changes with temperature. Investigation of non-dissociative electron attachment to C6H6 indicates that benzene anions are formed with lifetimes of ∼3 ps. Influence of a strong applied electric field on background processes like blackbody photoionization and collisional photo ionization, which complicate studies of Rydberg atom collision processes, is analyzed and the results presented.

An in depth study of both the predicted and actual imaging characteristics of an existing design for a multi-component relay lens was conducted. A numerical tolerancing analysis located a flaw in the current assembly procedure for the lens system. This procedure was then modified and an interferometric lens alignment station was designed and built to allow for highly accurate assembly of the multi-component lens. The system was then retested and a significant improvement in image quality was observed.

Absolute differential and integral charge transfer cross sections have been measured for 0.5, 0.85, 1.5, 2.8, and 5.0 keV O$\sp+$ with O$\sb2$ at scattering angles between 0.01$\sp\circ$ and 3.50$\sp\circ$ in the laboratory frame. The dependence of these cross sections upon the electronic state of the O$\sp+$ ion was investigated. This study was performed using a filter cell technique to derive the cross sections for both the $\rm O\sp+(\sp4S)$ ground state ions and the $\rm O\sp+({\sp2D,\ \sp2P})$ metastable state ions. The charge transfer cross sections involving the $\rm O\sp+({\sp2D,\ \sp2P})$ ions are significantly larger than the corresponding cross sections for the ground state ions. Previously published cross section measurements are compared to the present results for the total integral charge transfer cross sections of state-selected keV O$\sp+$ with O$\sb2$.

Low-energy electron transfer between a Rydberg atom and a target molecule can result in formation of long-lived metastable negative ions. Here we describe a novel permanent-magnet Penning trap designed to examine the lifetime of such long lived metastable negative ions. With the help of ion trajectory calculations, the characteristics of the trap have been investigated and the most effective methods for ion injection have been established. Collisions with SF6, which has a high electron attachment rate, result in the formation of SF-*6 ions which are known to have a long intermediate lifetime. Comparisons between experimental SF-*6 trapping data and ion trajectory calculations are discussed that demonstrate the capabilities of the trap. Future experimental studies are also proposed.

A 422 nm laser was constructed for the purpose of studying a strontium ultra-cold neutral plasma. Since strontium ions have atomic lines in the visible, we can optically image the plasma via the 88 Sr+ 2S1/2 → 2 P1/2 transition using 422 nm light. We produce light at this wavelength by converting infrared light at 844 nm from a commercial semiconductor infrared diode laser via second-harmonic generation in an semi-monolithic linear enhancement cavity. This thesis will cover the experimental details pertaining to nonlinear optics, optical resonator design, and locking electronics used to create a 422 nm laser.

This work describes intensity saturation of photoassociative transitions of 86Sr at the quantum mechanical unitarity limit. The saturation behavior, which results in a roll-over of the photoassociation rate for intensities greater than the saturation intensity, features interesting physics. Unlike other photoassociation spectroscopy (PAS) experiments, photoassociation occurs in a magneto-optical trap operating on the narrow dipole-forbidden transition at 689 nm. A laser red-detuned from the principal atomic transition at 461 nm by as much as 1300 GHz induces the photoassociation of ground state atoms to excited molecular states. Our previous studies [1] suggest that some of the PAS transitions for 86Sr are sensitive to the intensity of the laser. This work delves more deeply into these high intensity PAS effects, a subject that has not, to our knowledge, been studied experimentally for alkaline-earth atoms.

The diode laser system for laser cooling on the 1S 0 → 3P1 intercombination line of strontium discussed in this thesis allows us to cool and trap an atomic strontium sample to 15 muK. Samples in this temperature range are useful for the development of the next generation of atomic frequency standards, cold collision studies, and as a step towards quantum degeneracy. This laser system consists of a Littrow configuration external-cavity diode laser, which is frequency locked to a high finesse cavity. The cavity is subsequently locked to an absorption feature to produce a few mW of tunable, stabilized, single mode power at the target wavelength. We present the design and characterization of this system, including a linewidth measurement of 70 kHz, as well as preliminary results from cooling and trapping.

Collisions between atoms in high Rydberg states and polar targets can lead to the formation of dipole-bound negative ions. We examine the dynamics of CH3CN- ion production through electron transfer in K(np)/CH3CN collisions using velocity selected Rydberg atoms. The CH3CN- ion formation rate decreases markedly with decreasing Rydberg atom velocity, principally as a consequence of postattachment electrostatic interactions between the product ions. Implemented using Monte Carlo techniques, a curve-crossing model, which considers the effect of crossings between the diabetic potential curves for the covalent K(np)/CH3CN system and the K+/CH3CN - system, provides a clear explanation of several characteristics seen in electron transfer in K(np)/CH3CN collisions including: the n dependence in the CH3CN- ion production rate, the velocity dependence in the CH3CN- ion production rate, and the relatively small rate constant ∼0.5 - 1.0 x 10-8cm3 s-1 for production of long-lived CH3CN - ions.

This thesis describes the construction and characterization of a high energy, tunable, pulsed dye laser that is used to make ultracold strontium plasma. In order to make ultracold plasma, we cool and trap strontium atoms in a magneto-optical trap (MOT) and then photoionize them with the dye laser. The dye laser is pumped by high-energy 355nm pulses from a commercial Nd:YAG laser and it gives out 10ns pulses of 400--415nm light with up to 50mJ/pulse. We will discuss the lasers spectrum, wavelength calibration, output power and efficiency for photoionizing strontium.

No description available.