The need to improve the quality factor of Atomic Force Microscopy cantileversimmersed in fluid has been demonstrated in great length, especially in the caseswhere samples need to be in their natural liquid environment. For that reasona series of low pressure chemical vapor deposited silicon nitride cantilevers werecreated based on a series of defined parameters. Each cantilever had a fixed surfacearea of 5600μm2, comparable with the rectangular cantilever of dimension of 140μmby 40μm used as a reference. A procedure to fabricate these levers in a clean roomenvironment, as well as issues that came up during the fabrication, is explained indetail. Each measurement was done on our in-house setup. The main componentsof this apparatus are a focussed laser, a sample holder and a split photodiode. Theresults obtained were not as impressive as we had hope although some cantileversshowed a significant decrease in the quality factor, helping us direct future workon the subject. One cantilever (#9) did however show equivalent performance withrespect to the reference cantilever and even slightly increasing the quality factor ratioin the second mode. / Le besoin criant d'augmenter le facteur de qualité de micros-levier immergée dans un fluide utilisé en microscopie de force atomique a été démontré a mainte reprise, plus particulièrement dans le cas ou les échantillons devais être dans leur environnent liquide naturelle. C'est pour cette raison qu'une série de micro-levier ont été crée sur une basse de paramètre prédéfini et avec un dépôt de nitrure de silicium chimique en phase vapeur sous pression réduite. Chaque micros-leviers a une aire de surface de 5600μm2, pouvant ainsi être comparé avec le micro-levier de référence ayant pour dimension 140μm par 40μm. Une procédure pour fabriquer c'est micros-leviers dans un environnent de salle blanche, ainsi que les méthodes utiliser pour contrevenir aux problèmes encourus durant la fabrication, sont expliqués en détail. Chaque prise de mesure a été effectué sur notre appareil fait maison ayant comment composante principale un laser focalisé, un porte échantillon et une photodiode divisée. Les résultats obtenu n'ont pas été a la hauteur de nos attentes, néanmoins certain micros-leviers ont démontrés une réduction significative de leur facteur de qualité, nous aidant donc à diriger le travail futur sur le sujet. Un microlevier (#9), a par contre démontré une performance équivalente par rapport au micro-levier de référence augmentant même le ratio de facteur de qualité pour le 2e mode d'opération.

An experimental set-up consisting of an electron-impact induced ionization chamber, a quadrupole mass filter and an ion detector has been constructed. The operating characteristics of the quadrupole mass filter system have been examined and compared to the theoretical predictions. With a moderate mass resolution of 30, an absolute ion transmission efficiency of about 10% has been obtained. This system has been used to investigate the ionization efficiency of noble gases. Charged species up to He$ sp{2+}$, Ne$ sp{4+}$, Ar$ sp{6+}$, Kr$ sp{5+}$ and Xe$ sp{7+}$ have been studied. The behavior of the ionization efficiency curve near threshold is analyzed using a power law fitting approach. For the first and second degree ionization processes, the fitting power law coefficients k are found to be close to the charge number of the ions produced, in agreement with the theoretical predictions. The extracted ionization potentials also agree with the accepted values. For the third and higher degree of ionization, the k-values are generally much lower than the theoretical predictions. However, the extracted ionization potentials are still consistent with the accepted values.

Thesis (Ph.D.)--University of California, Berkeley, 2006. / (UMI)AAI3254097. Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1028. Adviser: Dmitry Budker.

The nitrogen-vacancy (NV) center in diamond is a solid-state point defect with an electronic spin that has accessible quantum mechanical properties. At room temperature, the electronic ground state sub-levels of the NV center can be initialized and read out using optical pumping, as well as coherently controlled using microwave frequency fields. This thesis focuses on using the spin state of the NV center for highly-sensitive magnetometry under ambient conditions. In particular, when the diamond surface is properly prepared, we demonstrate that NV centers can be used to measure the magnetic fluctuations stemming from individual molecules and ions attached or adsorbed to the surface. This thesis begins by introducing the physical and electronic structure of the NV center at room temperature, followed by the fundamental measurements that allow us to use the NV center as a sensitive magnetometer. Combining our sensitive NV center magnetometer with techniques from chemistry and atomic force microscopy (AFM), we demonstrate the all-optical detection of a single-molecule electron spin at room temperature. Finally, we discuss the time-resolved detection of individual electron spins adsorbing onto the surface of nano-diamonds. By extending our techniques to nano-diamonds, we move closer towards \textit{in vitro} magnetic field sensing that could be pivotal for better disease diagnosis and drug development. / Engineering and Applied Sciences - Applied Physics

A major consideration in opting for reliability and flexibility in Flexible Manufacturing Systems (FMSs) is to enhance the availability of resources in order to maintain an uninterrupted production. This means that sufficient redundancies must be foreseen at the preliminary production planning stage to cope with the random breakdowns of components. In this research effort four mathematical models were developed to determine the spare requirements for tooling system in FMSs, so that a desired system reliability is achieved with minimum cost and/or tool slots occupancy of the system. For the first time, the influences of tool sharing on cost, reliability, spares requirement, and tool magazines capacity of FMSs, in which tools and tool transporter are subject to general failure distributions, were analyzed. The developed models have been applied to a hypothetical example and the computational results were compared, for the case where tool sharing is not applicable and where tool sharing can be implemented. Several sets of sensitivity analysis were also performed on different system parameters through which the effects of the number of tools shared among machines, the required system reliability, and operating times for tools on the system reliability and cost were assessed.

No description available.

Dans cette thèse on présente des spectres inédits de l'argon et du krypton acquis à l'aide d'un spectromètre par impact électronique unique au monde. L'appareil est décrit en détails. On décrit aussi la méthode que l'on a employé afin de prédire théoriquement la position des niveaux de nos spectres. On présente des spectres d'électro-ionisation du krypton et de l'argon au-dessus de la seconde limite d'ionisation qui, pour les deux gaz correspond à des énergies dans l'ultraviolet lointain. Ces spectres sont riches en structures causées par la désexcitation d'ions négatifs qui ne sont observables que par cette méthode. On analyse les structures présentes dans chacun des spectres et on présente certaines similarités entre les spectres de ces deux gaz.

Cette thèse porte sur la prise de données nouvelles, à l'aide d'une méthode spectroscopique par impact électronique, pour l'étude des niveaux électroniques du néon dans les intervalles compris entre 42 eV et 43.1 eV et entre 43.2 eV et 44.5 eV. En plus, des prédictions basées sur les éléments isoélectroniques et sur l'extrapolation de séries de structures électroniques similaires a celles du néon ont été obtenues et ont conduit à l'interprétation des nouveaux spectres obtenus. Une interprétation est proposée aux structures qui étaient préalablement totalement inconnues entre 42 eV et 43.1 eV. Une étude détaillée de nos spectres de la zone comprise entre 43.2 eV et 44.5 eV nous a permis de confirmer certaines interprétations et d'en avancer de nouvelles.

In the present thesis we have investigated the lattice dynamics of diamond on the basis of the Cochran version of the dipole approximation model. Results have been presented for the dispersion curves, vibration spectra and Debye temperatures of diamond. We have also obtained the vibration spectra and Debye temperatures of germanium.

The contents of the present thesis can be described as follows. In chapter II the work of Hone (H60) is extended and the results are combined with those of Bailyn (B60). A unified approach is given to the derivation of the "proton-electron" dielectric function, with simplifications achieved by the removal of certain unnecessary transformations. A discussion of electron-electron screening shows why many of the results derived from Bailyn's and Hone's work are similar. In chapter III new derivations are given for the exchange and correlation terms obtained by several authors, namely Toya (T58), Hubbard (H57), Geldart-Vosko (G65), Kleinman (K67), and Takahashi (T68). We then show that electron-electron screening can be described in a more accurate way, and using a factorization procedure (introduced in chapter II), new expressions for the exhange and correlation term are obtained. In chapter IV we present the lattice dynamics of sodium, potassium and rubidium. Cochran's (C63) method of obtaining empirical effective potentials from the dispersion curves is discussed to obtain some insight into the problem. Then the method of Cowley et al (C66) is applied; a choice of the dielectric function is made, the pseudopotentials are determined and compared to those obtained by least squares fitting of different models. Finally, the dispersion curves are calculated and the interatomic potentials are also obtained.