Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2005. / Wartell, Roger, Committee Member ; Wilkinson, Angus, Committee Member ; Doyle, Donald, Committee Member ; Hud, Nicholas, Committee Member ; Williams, Loren, Committee Chair. Includes bibliographical references.

Thesis (Ph.D.) - University of St Andrews, April 2009.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2018. / This research investigates the absorption spectra of rubidium and the feedback control of an external cavity diode laser. This research is a necessary prerequisite for laser (Doppler) cooling and trapping of rubidium atoms. Cooling rubidium atoms down to such low temperatures can be achieved using the Doppler cooling technique. Here a laser is tuned to remain resonant with a speci c atomic transition. To do this, the absorption spectra of rubidium must therefore be observed. All of the above require a reasonable knowledge about topics such as atomic physics, laser cooling and trapping, feedback control systems, and absorption spectroscopy. A discussion of these topics is provided. We have utilised an experimental setup which allowed for measurements of the Doppler broadened and Doppler free absorption spectra of rubidium, as well the analysis of the Zeeman e ect on the Doppler free spectra. The setup consisted of a saturated absorption spectrometer for high resolution spectroscopy and a Michelson interferometer for calibrating our measurements. In analysing the Zeeman e ect we added a set of Helmholtz coils to the saturated absorption spectroscopy arrangement to measure the splitting of the hyper ne energy levels. / French South African Institute of Technology (F'SATI) National Research Foundation

Espectroscopia atômica em uma armadilha magneto-ótica / Atomic spectroscopy in a magneto-optical trap

The beta+-decay half-lives of the neutron-deficient, odd-odd, N = Z nuclei, 74Rb, 78Y, 82NB and 86Tc were measured following the fragmentation of a primary 92Mo beam at an energy of 60 MeV per nucleon at the GANIL laboratory, France. They were measured by correlating beta+-decays with the implantation of unambiguously identified fragments. The deduced log10 ft1/2-values are consistent with 0+→ 0+, Fermi superallowed transitions, which together with the measured beta+-detection efficiencies suggest T = 1, 1pi- 0+ ground states for these odd-odd, N = Z nuclei. These data represent the heaviest N = Z systems for which Fermi superallowed decays have been established. The results suggest that these nuclei can be used to extend the mass range used to test the Conserved Vector Current hypothesis of the standard model. In addition, an experiment using the reaction 58Ni + 28Si at a beam energy of 200 MeV was performed at the Laboratorio Nationale di Legnaro, Italy, using the EUROBALL spectrometer together with a charged particle silicon detector ball and an array of liquid scintillator neutron detectors. The measured values of the energies of the evaporated, charged-particles and those of the gamma-ray multiplicity (deduced using the liquid scintillator detectors), are used to implement a novel technique for the channel selection of weakly populated evaporation channels.

No description available.

The presence of quantized vortices and a high level of control over trap geometries and other system parameters make dilute-gas Bose-Einstein condensates (BECs) a natural environment for studies of vortex dynamics and quantum turbulence in superfluids, primary interests of the BEC group at the University of Arizona. Such research may lead to deeper understanding of the nature of quantum fluid dynamics and far-from-equilbrium phenomena.Despite the importance of quantized vortex dynamics in the fields of superfluidity, superconductivity and quantum turbulence, direct imaging of vortices in trapped BECs remains a significant technical challenge. This is primarily due to the small size of the vortex core in a trapped gas, which is typically a few hundred nanometers in diameter. In this dissertation I present the design and construction of a new ^87Rb BEC apparatus with the goal of studying vortex dynamics in trapped BECs. The heart of the apparatus is a compact vacuum chamber with a custom, all-glass science cell designed to accommodate the use of commercial high-numerical-aperture microscope objectives for in situ imaging of vortices.The designs for the new system are, in part, based on prior work in our group on in situ imaging of vortices. Here I review aspects of our prior work and discuss some of the successes and limitations that are relevant to the new apparatus. The bulk of the thesis is used to described the major subsystems of the new apparatus which include the vacuum chamber, the laser systems, the magnetic transfer system and the final magnetic trap for the atoms. Finally, I demonstrate the creation of a BEC of ~2x10^6 ^87Rb atoms in our new system and show that the BEC can be transferred into a weak, spherical, magnetic trap with a well defined magnetic field axis that may be useful for future vortex imaging studies.

This dissertation reports high-resolution experimental study and numerical analysis of the rubidium dimer 31Πg, "6" ^"1" "Σ" _"g" ^"+" , "3" ^"3" "Π" _"g" , and "4" ^"3" "Σ" _"g" ^"+" excited electronic states. The term energies of over 2 400 observed ro-vibrational levels spanning a large range of rotational and vibrational quantum numbers were measured with the perturbation facilitated optical-optical double resonance technique 24 000 cm-1 – 26 000 cm-1 above the ground state minimum of Rb2. The excited electronic states were probed by exciting Rb2 molecules from the thermally populated ro-vibrational levels of the "X" ^" 1" "Σ" _"g" ^"+" ground electronic state through intermediate levels of the mixed" " "A" ^"1" "Σ" _"u" ^"+" " ~ " "b" ^"3" "Π" _"u" electronic states. Probe laser resonance was detected by measuring the laser induced fluorescence from the excited electronic states to the "a" ^"3" "Σ" _"u" ^"+" triplet ground state. The ro-vibrational term energies from each electronic state were fit to molecular constants using the Dunham expansion. These molecular constants were subsequently used to generate Rydberg-Klein-Rees model potential energy functions. The spin multiplicity of the electronic states as well as the vibrational numbering of the triplet electronic states were determined by resolving the bound-free emission from the excited ro-vibrational levels to the triplet ground state. / Physics

No description available.

Thermal methods of high precision were used to determine the solid-liquid phase equilibria diagrams for the potassium-rubidium and the rubidium-cesium systems. Both form minima in the liquidus curves occurring at 307.00° K with 0.667 mole fraction rubidium in the potassium-rubidium system and 282.85° K with 0.530 mole fraction cesium in the rubidium-cesium system. In the potassium-rubidium system, the liquidus and solidus points are very close together, giving a very narrow temperature range for the two phase region. The freezing point minimum in the potassium-rubidium system occurs at 0.667 mole fraction rubidium, suggesting the possible formation of a KRb2 intermetallic compound.