Using scanning tunneling microscopy (STM) we have explored complex surface adsorbed molecules, nanocars, on Au(111) and the parameters related to the direct translation of these molecules by the STM tip. Specifically, the molecules focused on here were functionalized with C 60 or trans ruthenium complexes. With low tunneling currents the molecules could be imaged at room temperature. Increasing the tunneling current allowed us to bring the tip closer to individual molecules and reposition them on the surface. Below specific current and bias voltage conditions the molecules remained stationary, while in other cases the tip interaction was strong enough to drastically damage or eject the molecule from the field of view. High temperature scans revealed the effect of the wheel activation energy relative to the underlying surface as the different wheeled nanocars began diffusing at different temperatures confirming the manipulation measurements.

Examination of quantum critical points of itinerant electron systems will aid with understanding of d-electron magnetism that exhibits both local and itinerant characteristics in different families of compounds. Doping-induced quantum phase transition of the itinerant ferromagnet Sc 3.1 In that is composed of non-magnetic elements is the focus of our work. Polycrystalline samples of (Sc 1-x Lu x ) 3.1 In with 0≤ x≤ 0.08 were prepared by arcmelting and then annealing for an extended period of time. Susceptibility measurements were performed in an applied magnetic field H = 0.1 T for temperatures T = 1.85 K to 300 K. Linearity of Arrott plots in low-field region was significantly improved by implementing the non-mean-field Arrott-Noakes technique where plotting M 1/β vs. ( H/M ) 1/γ is used to determine both the Curie temperature and composition. Modified Arrott plot approach was used in order to determine the new critical exponents β, γ and δ that better describe this compound. The Curie temperature of the Sc 3.1 In compound was found to be T C = 4.4 K and the critical composition x c = 0.02. This work was supported by NSF DMR 0847681.

Quasi-one-dimensional Rydberg atoms exposed to alternating positive and negative electric field pulses (kicks) are an example of a chaotic atomic system. Chaotic ionization is predicted in this system via a phase space turnstile mechanism, and we have explored this experimentally. Turnstiles form a general transport mechanism for numerous chaotic systems, and this study is the first to explicitly illuminate their relevance to atomic ionization. Two experiments are presented. In the first we show that the ionization of the electron depends not only on the initial electron energy, but also on the phase space position of the electron with respect to the turnstile--that part of the electron packet inside the turnstile ionizes quickly, after one period of the applied field, while that part outside the turnstile ionizes after multiple kicking periods. In the second experiment we show the signature of the turnstile manifests itself in the step-function-like behavior of the ionization fraction as a function of the kick strength. This behavior persists for different values of kicking periods and starting electron energies.

In this thesis we describe a new version of a magneto-friction model, which was developed for computing the magnetospheric equilibrium that includes an arbitrary Earth's dipole tilt and interplanetary magnetic field. We also describe the algorithms of this new friction code that trace magnetic field lines, locate the neutral sheet, and identify the magnetopause In addition, we present a generalized theory for calculating magnetic flux tube volume in the magnetotail, in an attempt to generalize the Wolf [2006] empirical formula, and describe a method for estimating flux tube volume from measurements at geosynchronous orbit. This new method has been tested against various equilibrated magnetospheres generated by the new friction code. Although still incomplete, the method exhibits promising features, and is to be completed in the future.

This thesis presents calculations of the magnetic helicity injection due to rotating sunspots and a determination of the characteristics of the rotating sunspots in the active regions with simple magnetic configurations. Four active regions are investigated to study the relationship between rotating sunspots and magnetic helicity. The observations indicate that significantly more helicity is injected during the period of rotation in polarities with strong magnetic field. This may be a result of the emergence of a magnetic flux rope from below the solar surface. Moreover, our preliminary study on a large sample of 90 active regions shows that the level of flaring activity increases with the rate of helicity injection. Finally, a statistical study is carried out to determine the relation between rotating sunspots and the emergence of magnetic flux tubes. Among 82 active regions which exhibit flux emergence, 93% are associated with rotating sunspots. Among 50 active regions without well-defined flux emergence, 60% of sunspots are observed to be rotating, though relatively slowly. In addition, we find that sense of the rotation (i.e., clockwise or counter-clockwise) of the sunspots shows a weak hemispherical tendency.

The goals of this thesis were to design and synthesize new stable radicals and to study their properties. The attempted synthesis of new stable thioaminyl, verdazyl, and dioxadiazinyl radicals is described. Successfully prepared radicals were characterized by spectroscopic methods. The synthesis of new thioaminyl radicals and diradicals was attempted. Preparation of thioaminyl precursors, the sulfenamides, was accomplished with sulfenyl chlorides and amines. Oxidation with DDQ yielded radicals which decomposed back to the sulfenamides within 1–2 minutes. A bis(sulfenamide) was synthesized using a sulfenyl chloride and an appropriate bis(amine). The structure of the bis(sulfenamide) was confirmed by NMR spectroscopy and x-ray crystallography. Oxidation of the bis(sulfenamide) to the thioaminyl diradical was unsuccessful. New phosphaverdazyl radicals were prepared and studied using EPR spectroscopy. The phosphaverdazyl precursors, the tetrazines, were prepared from the corresponding bis(hydrazides). The tetrazines were oxidized with benzoquinone to yield phosphaverdazyls. The phosphaverdazyls prepared do not share the same level of stability as the parent carbon-based verdazyls; they slowly decompose back to tetrazines. Incorporation of phosphorus into the verdazyl core has several effects on the properties of the radical relative to the parent verdazyl system. Through a combination of EPR and computational studies, it was concluded that the geometry of the verdazyl ring and the electronic nature at phosphorus appear to be sensitive to the nature of the substituents attached to phosphorus. Exocyclic “spin-leakage” was observed for one phosphaverdazyl, which can be rationalized using a spiroconjugative mechanism. The phenomena of spiroconjugation was further explored through the synthesis of a phosphaverdazyl derivative attached to phosphazene in a spirocyclic manner. Synthetic routes to the hitherto unknown dioxadiazinyl system were explored. An intermediate hydroxyamidoxime was synthesized and fully characterized. Cyclization reactions of the hydroxyamidoxime to putative dioxadiazines were carried out using aldehydes and a ketone. The cyclization products could not be unambiguously assigned. The cyclization products can be rationalized as the desired dioxadiazine or the 5-membered oxadiazolidine. One derivative was oxidized to a persistent radical, the EPR of which is consistent with a nitroxide structure. / Graduate

Laser Induced Fluorescence (LIF) is one of the chief methods for detecting ambient hydroxyl radicals. To measure the absolute concentration of this important atmospheric chemical species, accurately known quenching rate constants due to the dominant gases in the air are of paramount importance. Unfortunately, these rate constants have only been measured under conditions remote from those of ambient air. This dissertation reports the measurement of the rate constants of water, argon, nitrogen and oxygen under ambient conditions. As the LIF is carried out at atmospheric pressure, the OH fluorescence life-time becomes extremely short (about 1 ns). Time Correlated Photon Counting was used to study this short fluorescence phenomenon. The unique feature this study was that the deactivation processes of the excited OH could be described completely by a kinetic model. Detailed theoretical treatments of the LIF processes are presented. The data obtained are consistent with the accepted model, thereby demonstrating the usefulness and validity of the experimental approach. The rate constants (cc molecule('-1) sec('-1)) for quenching by water and argon were accurately measured. The vibrational relaxation rate constant by water (3.4 (+OR-) 0.6 x 10('-10)) is the first value ever reported, while the electronic quenching rate constants for water (k(,Q0) = 7.9 (+OR-) 0.47 x 10('-10), k(,Q1) = 1.48 (+OR-) 0.74 x 10('-10)) are the first measured at atmospheric pressure. The electronic quenching rate constants of the ('2)(SIGMA)(v' = 1) state (k(,Q1)) and the ('2)(SIGMA)(v' = 0) state (k(,Q0)) by argon are k(,Q0) = 0.48 (+OR-) 0.14 x 10('-12) and k(,Q1) = 0.24 (+OR-) 0.06 x 10('-11). The vibrational relaxation rate constant by argon is k(,10) = 0.34 (+OR-) 0.06 x 10('-11). The rate constants for oxygen (k(,Q1) (+OR-) k(,10) = 1.83 (+OR-) 0.43 x 10('-9) and k(,Q0) = 2.6 (+OR-) 0.6 x 10('-10)) are significantly higher than the limited measurements available at low pressure. The rate constants for nitrogen are k(,Q0) = 0.71 (+OR-) 0.08 x 10('-11) and k(,10) = 8.07 (+OR-) 0.65 x 10('-11). All these values are the first obtained at atmospheric pressure and although shown to be consistent with the widely scattered low pressure values, they allow more reliable analysis of ambient OH measurements, and result in a 31.2% increase in the published values.

An extensive literature has been established on the use of high frequency conductometric methods in chemical analysis and research. The fact that the instruments respond to chemical changes without having electrodes immersed in the reacting solutions has attracted the attention of many investigators. Until the last few years, practically all of the investigations were concerned with aqueous solutions, with the exception of measurements of dielectric constants. There seemed no logical reason for not extending the use of the high frequency instruments to the study of Bronsted acid-base reactions, organic syntheses, rates of reaction, and the other commonly studied aspects of non-aqueous chemistry. A few early works were published with regard to esterifications and the titration of weak acids in organic solvents; but no extensive reports were forthcoming on the general utility of high frequency titrimetry in non-aqueous systems until the paper of Grove and Jeffrey (1960). Since 1960, an increasing interest has been shown in nonaqueous use of high frequency titrimeters, as well be shown in the next chapter. It seemed only a matter of time until someone would perform the research necessary to allow the use of solvents which could be kept in the liquid state (at atmospheric pressure) only at low temperatures. The classical example of such a solvent is liquid ammonia which boils at -33.4°C., but a great deal of work has been done in other low temperature solvents such as sulfur dioxide, hydrogen cyanide and hydrogen fluoride. A major obstacle to the use of such low temperature liquids with high frequency titrimeters was the lack of a suitable cell; one which could maintain the low temperature necessary to preserve the liquid state for the protracted periods of time required to perform titrations. Thus it was th purpose of the present investigation to develop a cell which would permit the use of high frequency titrimeters for studying low temperature, nonaqueous solvents--specifically ammonia. On the assumption that a suitable cell could be constructed, a further aspiration of the research was to investigate the response of high frequency titrimeters to a sufficient number of liquid ammonia reactions to show that an attractive area of chemical research had been exposed by the development of the cell.

The present work is a polarographic study of the alkali metals and selected first row transition metals in DMSO (dimethylsulfoxide) with tetraethylammonium perchlorate as a supporting electrolyte. DMSO was chosen as a solvent because of its interesting solvent and complexing properties. Tetraethylammonium perchlorate was chosen as a supporting electrolyte because of its lack of complex forming tendencies and because of the wide range of voltages available for polarographic investigation before the supporting electrolyte ions react electrochemically. One of the problems, particularly in nonaqueous polarography, is the low conductivity of the solutions leading to high cell resistance. As current flows through the cell, additional voltage must be applied to overcome the “I R” voltage drop in the cell. By measuring the cell resistance while the polargram is being run and knowing the current flowing, one can correct the half-wave potentials, although this becomes rather tedious where large numbers of polarograms are to be taken. A more elegant approach to the problem is the use of the three-electrode polarographic cell and a controlled potential polarograph similar to the one developed by Kelley, Fisher, and Jones (26). A description of an instrument of this type that was used in all of the work reported in this paper is given later in the work.

A polarographic study of the complexes of selected metal ions and the p-Tosyl derivatives of the amino acids; glycine, glutamic acid and lysine has been made to determine their coordination number, formula, dissociation constant and free energy of formation.