<p> Using atomic beam magnetic resonance techniques the hyperfine structure (hfs) constants for the magnetic dipole and electric quadrupole interaction, AJ and BJ, have been measured for the following isotopes: 40-hour 140La, 1.8-hour 149Nd and 11-day 147Nd.</p> <p> For 140La the hfs constants are (relative to the J = 5/2 state of 2D) |A5/2| = 55.9(4) MHz, |B5/2| = 38(4) MHz, B5/2/A5/2 > 0. Application of the Fermi-Segre relations in comparison with 139La yields the nuclear moments; μI = (+)0.73(3) n.m., and Q =(+)0.11(4) b. The adopted signs are based on Blok's measured sign of Q for 140La.</p> <p> For 149Nd the hfs constants are: |A4| = 91.0(19) MHz, |B4| = 266(53) MHz, and B4/A4 > 0. Comparison with 145Nd yields μI = (-)0.350(10) nm., and Q = +1.3(3)b. The signs of these moments are based on Q>0 as indicated by nuclear systematics in this region.</p> <p> For 147Nd the hfs constants are |A4| = 143(4) MHz, |B4| = 181(64) MHz, and B4/A4 > 0. Comparison with 145Nd yields |μI| = 0.553(15) n.m., |Q| = 0.9(3) b and μI/Q <0.</p> <p> The error in the 140La magnetic moment allows for a possible 2% hfs anomaly. The quadrupole moments allow for a possible 25% error in the core polarization correction (Sternheimer).</p> <p> These results are discussed in terms of the shell model, the quasi-particle model, and the Nilsson model.</p> / Thesis / Doctor of Philosophy (PhD)

Neste trabalho realizamos medidas espectroscópicas de alta resolução nas bandas vibracionais da transição A1&#8721;+u&#8594;X1&#8721;+g do dímero de Sódio, produzido a partir da expansão supersônica do vapor deste metal no vácuo. Para determinação das constantes moleculares utilizamos técnicas alternativas de espectroscopia óptica de alta-resolução, tais como: Fluorescência Ressonante, Raman Estimulado e Depopulação Óptica. As duas últimas técnicas utilizam dois campos de laser, por isso são também chamadas de técnicas de campo duplo e proporcionam a simplificação do espectro de Fluorescência Ressonante, ajudando no seu entendimento e no cálculo das constantes moleculares dos estados estudados. Desenvolvemos também um método de obtenção de padrões de interferência, baseado no método proposto por Ramsey, a partir da modulação espacial da população do estado fundamental de um sistema aberto de dois níveis quaisquer. Foi possível obter franjas de interferência na região visível, sem que haja necessariamente coerência entre estados atômicos, efeito este observado pela primeira vez na literatura. / This work reports measurements in the vibrational bands of the A1&#8721;+u&#8594;X1&#8721;+g transition for Sodium dimer, produced in a supersonic expansion of the metal vapor into the vacuum. For the determination of the molecular constants we used righ-resolution laser spectroscopy techniques: Resonance Fluorescence, Stimulated Raman and Optical Depletion. The two last techniques need two lasers fields and provide the simplification of the Resonance Fluorescence spectrum, suitable for the tine assignment. We have also developed a new method to obtain Ramsey-like fringes in the optical region, due to a spatial modulation of the ground state population of any open two-level system. Tbe fringes were obtained without any atomic coherence of the levels, which is an effect observed in the literature for the first time.

O trabalho trata da desaceleração de feixes de átomos neutros de Sódio, pela técnica de sintonia Zeeman. O processo de desaceleração é estudado em detalhes e demonstrado com a utilização de um único laser. É feito o estudo do seguimento adiabático do átomo em relação ao campo magnético e demonstrada sua importância no processo de produção de fluxos intensos de átomos lentos. A posição em que os átomos param foi modificada, através da mudança do perfil do campo magnético onde os átomos se movimentam, levando-os para uma região de fácil acesso. A forma peculiar da distribuição espacial dos átomos ao atingirem o repouso é explicada e, finalmente, é estudada a focalização dos átomos, através de um campo magnético hexapolar, e o aprisionamento de átomos em uma armadilha magnética / This work describes the deceleration a sodium atoms beam by means of the Zeeman tuning technique. The deceleration process is studied in details and its demonstration is made using a single laser. We have studied and present the adiabatic following of the atoms along the magnetic field and its relevance to produce slow, high density, flux of neutral atoms. The atoms\' stopping position was varied, by changing the magnetic field profile, in a way to produce slows atoms outside the solenoid. The peculiar shape of the atomic spatial distribution of atoms at rest is explained, the focusing of atoms though a hexapole magnetic field is studied and the trapping of atoms in a magnetic trap is demonstrated

O trabalho trata da desaceleração de feixes de átomos neutros de Sódio, pela técnica de sintonia Zeeman. O processo de desaceleração é estudado em detalhes e demonstrado com a utilização de um único laser. É feito o estudo do seguimento adiabático do átomo em relação ao campo magnético e demonstrada sua importância no processo de produção de fluxos intensos de átomos lentos. A posição em que os átomos param foi modificada, através da mudança do perfil do campo magnético onde os átomos se movimentam, levando-os para uma região de fácil acesso. A forma peculiar da distribuição espacial dos átomos ao atingirem o repouso é explicada e, finalmente, é estudada a focalização dos átomos, através de um campo magnético hexapolar, e o aprisionamento de átomos em uma armadilha magnética / This work describes the deceleration a sodium atoms beam by means of the Zeeman tuning technique. The deceleration process is studied in details and its demonstration is made using a single laser. We have studied and present the adiabatic following of the atoms along the magnetic field and its relevance to produce slow, high density, flux of neutral atoms. The atoms\' stopping position was varied, by changing the magnetic field profile, in a way to produce slows atoms outside the solenoid. The peculiar shape of the atomic spatial distribution of atoms at rest is explained, the focusing of atoms though a hexapole magnetic field is studied and the trapping of atoms in a magnetic trap is demonstrated

Neste trabalho realizamos medidas espectroscópicas de alta resolução nas bandas vibracionais da transição A1&#8721;+u&#8594;X1&#8721;+g do dímero de Sódio, produzido a partir da expansão supersônica do vapor deste metal no vácuo. Para determinação das constantes moleculares utilizamos técnicas alternativas de espectroscopia óptica de alta-resolução, tais como: Fluorescência Ressonante, Raman Estimulado e Depopulação Óptica. As duas últimas técnicas utilizam dois campos de laser, por isso são também chamadas de técnicas de campo duplo e proporcionam a simplificação do espectro de Fluorescência Ressonante, ajudando no seu entendimento e no cálculo das constantes moleculares dos estados estudados. Desenvolvemos também um método de obtenção de padrões de interferência, baseado no método proposto por Ramsey, a partir da modulação espacial da população do estado fundamental de um sistema aberto de dois níveis quaisquer. Foi possível obter franjas de interferência na região visível, sem que haja necessariamente coerência entre estados atômicos, efeito este observado pela primeira vez na literatura. / This work reports measurements in the vibrational bands of the A1&#8721;+u&#8594;X1&#8721;+g transition for Sodium dimer, produced in a supersonic expansion of the metal vapor into the vacuum. For the determination of the molecular constants we used righ-resolution laser spectroscopy techniques: Resonance Fluorescence, Stimulated Raman and Optical Depletion. The two last techniques need two lasers fields and provide the simplification of the Resonance Fluorescence spectrum, suitable for the tine assignment. We have also developed a new method to obtain Ramsey-like fringes in the optical region, due to a spatial modulation of the ground state population of any open two-level system. Tbe fringes were obtained without any atomic coherence of the levels, which is an effect observed in the literature for the first time.

<p> The atomic beam magnetic resonance technique with radioactive detection has been used to investigate the hyperfine structure of In^117m. The present research is based on the work done by Cameron (1962) who could not obtain accurate values for the hyperfine interaction constants due to the low neutron flux at the time in the McMaster reactor.</p> <p> This thesis is an account of an attempt to complete that experiment by observing the field independent direct hyperfine transitions. The theory of the experiment, the apparatus and techniques, and the method of data analysis are described. Because of the counting errors, the data are not as conclusive as had been hoped. If the resonances have, in fact, been seen, then the results are: a1/2 = -932.996 ± 0.012 Mc/sec a3/2 = -99.005 ± 0.005 Mc/sec μI = -0.25146 ± 0.00003 nuclear magnetons.</p> / Thesis / Master of Science (MSc)

Atomic beam magnetic resonance techniques have been used to investigate the properties of the 41-second isomeric state of silver-109 and the 32-minute ground state of the fission product cesium-138. A description of the apparatus and of the atomic beam method for the determination of nuclear moments is given. The results obtained for silver-109m are: I= 7/2 a(2S1/2) = 9477±13 Mc/sec μ1 (uncorrected) = 4.31±0.04 nuclear magnetons 109Δ109m = -(1.1±1.2)%. The value of the moment confirms that the proton configuration is (g9/2)^-3 7/2. In the course of this experiment, multiple quantum Zeeman transitions were observed between levels in both the F = I + 1/2 and F = I - 1/2 hyperfine multiplets. The results obtained for cesium-138 are: I =3 Δv = 1650 +650 -250 Mc/sec |μI| (uncorrected)= 0.45 +0.18 -0.07 nuclear magnetons. For these experiments simultaneous detection of both the resonant and thrown out portions of the beam was used for the first time in this laboratory. / Thesis / Doctor of Philosophy (PhD)

This thesis presents an in-depth study into the characterization and enhancement of a metastable neon laser cooled and trapped atomic beam. The apparatus consists of a standard Zeeman slowed atomic beam loaded into a magneto-optical trap and was designed for applications to electron scattering experiments and photoionization. The efficiency of the metastable neon atomic source was investigated to determine the ideal cathode type for maximum metastable production and optimal atomic beam velocity haracteristics. A series of characterization measurements were performed on the MOT, and the trap volume and population were investigated for a range of trapping and slowing laser intensities and detunings, together with the MOT and Zeeman slower magnetic fields. The volume measurements were compared to standard Doppler theory and it was found that the Doppler model inadequately explained the trap behaviour. It was found that the MOT population characteristics were governed by two processes: two-body losses that limit the trap population at high densities, and the efficiency of the atom capture process which limits the operational range of the MOT over the various parameters. The trap temperature was determined to be 1.3mK via a time-of-flight technique. This was nearly twice that predicted by Doppler theory and the lack of agreement once again suggests the inadequacies in the Doppler theory to correctly model the experiment. The application of the MOT to the photoionization cross-section measurement of the (2p53p)3D3 state of neon was investigated. The MOT decay technique was utilized to measure cross-section values of o351 = 2.9+0.2 -0.3 x 10 -18cm2 and o363 = 3.1 +0.3 -0.4 x 10-18cm2 at the wavelengths of 351nm and 363nm respectively. This is an increase in accuracy of around a factor of five from previous measurements and it was found that the results agreed well with the values predicted by current theories.

Interest exists in the development of transparent conducting oxide materials, which have diverse applications in areas such as transparent coatings for display technologies, solar cells, and optoelectronics. Since many of the applications require the use of thin film forms, the need is to establish useful experimental approaches to the fabrication of such structures. One relatively new method in this area is oxygen-plasma assisted atomic beam epitaxy (OPABE) in which oxide layers are grown under normal molecular beam epitaxy (MBE) conditions with the addition of an oxygen atom beam to ensure full oxidation of the depositing metallic species. Work in this area has to date mainly focussed on the growth of relatively stable oxides such as ZnO, MgO and In₂O₃ which are the strongly thermodynamically favoured reaction products, across a broad range of reaction conditions. In contrast, the present work is concerned with the growth of Cu2O and a range of delafossite materials, namely CuInO₂, CuCrO₂ and CuGaO₂, which are expected to require much more sensitive control to achieve the desired reaction product. Studies of the OPABE growth of Cu₂O on MgO (100) and MgO (110) substrates have been carried out, using a broad range of physical techniques to characterise the grown Cu₂O deposits. It is demonstrated that CuO is the favoured reaction product at low growth temperatures, although Cu₂O becomes increasingly favoured as the growth temperature increases. Alternatively, it is also shown that a novel bilayer growth method, whereby some pure Cu is deposited prior to oxide growth, can be used to form the desired Cu (I) phase. Varying crystal orientations are seen, depending on the exact growth conditions; core level and valence band X-ray photoelectron spectroscopy (XPS), optical band gap and atomic force microscopy (AFM) measurements are used to characterise the deposits. Further growth investigations of the delafossite compounds CuInO₂, CuCrO₂ and CuGaO₂ using OPABE are also recorded, and for the case of CuInO₂, comparison is also made with the pulsed laser deposition approach. For all three materials systems, oriented crystal growth on basal planes sapphire substrates is seen, with either the (001) plane or the (015) plane orienting parallel to the substrate depending on the growth temperature, provided approximately correct metal fluxes are used as set by the Knudsen-cell temperatures. The typical valence band electronic structure of delafossite materials is observed in all three cases, and XPS peak shifts suggest that the layers can be electrically doped by adding appropriate metal fluxes during growth. AFM measurements show the grown films are relatively rough and it is suggested that the growth mode follows an island growth mechanism in which oriented three dimensional islands formed at the start of growth gradually enlarge and coalesce as the film thickens. Optical absorption measurements are consistent with the generally accepted optical band gaps of the materials concerned.

The doctoral thesis presents the diagnostic neutral lithium beam on the COMPASS tokamak in Prague. The technical part describes the system for injection of accelerated lithium beam into the COMPASS tokamak and the respective detection systems for beam emission spectroscopy. The physical part describes the analysis of measured spectroscopic data, with particular emphasis on density fluctuations in the edge plasma. Detailed analysis of turbulent structures outside of the confined plasma region is presented, as well as investigations of the ELM instabilities during high confinement mode plasma operation. The thesis also presents the development and proof-of-concept measurements of a new and unique diagnostic method - atomic beam probe. The method uses detection of the ionized part of the beam for current density profile measurements in the plasma edge.