In this thesis, we investigated the surface composition and orientation of both pure room-temperature ionic liquids (Ils) and binary mixtures of the ILs of the type consisting of the 1-alkyl-3-methylimidazolium ([C[subscropt n]mim]���, n=4, 8, and 12) cation coupled with either [PF���]���, [BF���]���, [Cl]���, or [Br]���. The surfaces of the ILs were examined using both direct recoil spectrometry (DRS) and surface tension measurements. With DRS, a spectral signal produced by a recoiled surface atom indicates the existence of a particular molecular or ionic species at the interface. Derived from the signal are the atomic ratios, which are strongly dependent on the surface orientation of the surface species. The DRS findings are complimented with surface tension measurements, and the thermodynamics properties (surface enthalpy and entropy) derived from such measurements are related to the surface composition and orientation. From the experiments on the neat ILs, the surface compositions of the imidazolium-based ILs were determined. Furthermore, the effects of systematic variations of the cation size (the length of the 1-alkyl chain) and anion identity on the surface orientation of the organic cation were also examined. The surfaces of binary mixtures containing ~25 mol % of [C������mim][PF���] or [C������mim][BF���] in [C���mim}[BF���] were also investigated. The DRS and surface tension data of the mixtures were compared to those of the pure components to determine the composition and any changes in the orientations of the cations upon mixing. / Graduation date: 2004

Buildings, maps and objects et cetera, can be modeled using a computer or reconstructed in 3D by data from different kinds of cameras or laser scanners. This thesis concerns the latter. The recent improvements of Time-of-Flight cameras have brought a number of new interesting research areas to the surface. Registration of several ToF camera point clouds is such an area. A literature study has been made to summarize the research done in the area over the last two decades. The most popular method for registering point clouds, namely the Iterative Closest Point (ICP), has been studied. In addition to this, an error relaxation algorithm was implemented to minimize the accumulated error of the sequential pairwise ICP. A few different real-world test scenarios and one scenario with synthetic data were constructed. These data sets were registered with varying outcome. The obtained camera poses from the sequential ICP were improved by loop closing and error relaxation. The results illustrate the importance of having good initial guesses on the relative transformations to obtain a correct model. Furthermore the strengths and weaknesses of the sequential ICP and the utilized error relaxation method are shown.

The production and distribution of counterfeit drugs is a serious worldwide health problem. One recent example is the appearance of fake artesunate antimalarial tablets in Southeast Asia. Due to the malevolent circumstances in which these fakes are produced, concern over the presence of toxic tablet ingredients is very much a legitimate health issue. Therefore, quantification of the amount of active ingredient present in tablets marketed as artesunate, a drug used for the treatment of the multidrug-resistant Plasmodium falciparum malaria in Southeast Asia required liquid chromatography coupled to mass spectrometry (LC-MS). This quantification allows the classification of the tablets as genuine, sub-therapeutic or fake and the validation of field results using colorimetric tests. During the LC-MS experiments, there were the observations that several of the samples contained a “wrong” active ingredient (AI). This was identified via accurate mass measurements, chromatographic retention time and in-source collision-induced dissociation (CID)as erythromycin, a common antibiotic. Using multivariate unsupervised clustering algorithms, the LC-MS data was utilized for “chemically fingerprinting” the fake tablet samples and investigating the similarities between them. The results of this initial survey show a correlation between sample origin, the different types of fake authentication holograms found in the packaging and sample composition.

In this thesis we synthesize discotic liquid crystal materials. After demonstrating the molecular structures by 1H-NMR of Acid-6, we measure the properties of this material. We use discotic liquid crystal Acid-6 and measure its¡¦ properties. It shows the properties of Acid-6 which is having the ability of absorbing visible light. By UV-Vis spectrum, we can realize the absorption band is located at 400 nm and confirm that it is able to be a photo-sensitized dye. Besides, the property of discotic liquid crystal is the self-assembly ability, the molecular can assemble into hexagonal columnar structure by themselves, which enable discotic liquid crystal to have better mobility. The DSSCs have good power conversion efficiency with using discotic liquid crystals Acid-6. We can measure its¡¦ mobility to know the component with which the most appropriate.

In this thesis, we investigated charge carrier properties of two series of organic semiconductors with time of flight measurement. Charge carrier mobility is calculated in different electron filed and fitted to Poole-Frenkel model. In the first part, we investigated carrier properties of pyrrole derivatives .The mea- surement result of pyrrole derivatives with different functional group indicate that trans- port properties may effected by this different functional group and the bonding position. There have two different type of transport properties that is single transport and bipolar transport. In addition, carrier mobility have more than two order difference with this different functional group. Finally, we investigated carrier properties of anthracene derivatives. The measure- ment result indicate that the intermolecular aggregation can be solved by synthesizing another functional group to form polymer. This method not only perform excellent thin film stability but also keep bipolar transport property after synthesizing.

The construction of a liquid nitrogen-cooled ion mobility spectrometer coupled with time-of-flight mass spectrometry was implemented to demonstrate the ability to discriminate between electronic isomers. Ion mobility allows for the separation of ions based on differing cross-sections-to-charge ratio. This allows for the possible discrimination of species with same mass if the ions differ by cross-section. Time-offlight mass spectrometry was added to mass identify the separated peak for proper identification. A liquid nitrogen-cooled mobility cell was employed for a two-fold purpose. First, the low temperatures increase the peak resolution to aid in resolving the separated ions. This is necessary when isomers may have similar cross-sections. Second, low temperature shortens the mean free path and decreases the neutral buffer gas speeds allowing for more interactions between the ions and the drift gas. Kr2+ study was performed to verify instrument performance. The variable-temperature ion mobility spectrometer was utilized to separate the distonic and conventional ion forms of CH3OH, CH3F, and CH3NH2 and to discriminate between the keto and enol forms of the acetone radical cation. Density functional theory and ab initio calculations were employed to aid in proper identification of separating isomers. Monte Carlo integration tools were also developed to predict ion cross-section and resolution within a buffer gas.

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains ix, 99 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (Ph. D.) in Physics--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 153-158).

In this dissertation, I will look into the size distribution of silver nanoparticles produced by laser ablation of microparticles (LAM). I will investigate the role of both pulsed and continuously operating nozzles on the size distribution. In addition, I will examine any deviations from the previously observed log-normal size distribution for silver nanoparticles comparing previous collection techniques involving supersonic jet impaction with a current time of flight mass spectrometer (TOF-MS). These new observations will be made in situ using a Wiley-McLaren TOF-MS with a reflector and multiphoton ionization and will mainly focus on the smaller sized nanoparticles. An introduction to enhancing a second harmonic optically generated signal will also be investigated involving silver nanocomposites while utilizing a polarized crossed-beam femtosecond laser technique. / text

This dissertation presents dissociation mechanism and dissociation kinetics studies of gas-phase ions using mass spectrometry (MS). Dissociation of a gas-phase ion is related to its fundamental properties such as composition and structure. However, the detailed processes, internal energy deposition during ion activation as well as the mechanism of dissociation, are not fully known. In the present work, ion structural studies from which mechanisms can be inferred were performed using infrared multiphoton dissociation (IRMPD) spectroscopy, soft-landing, IR spectroscopy, and quantum chemical calculations. Kinetics studies involved instrument modification to add surface-induced dissociation (SID) capability and peak shape analysis. Structural studies were performed to determine dissociation mechanisms. The b₂⁺ ion from AGG is an oxazolone structure as indicated by the IRMPD spectrum and quantum chemical calculations. Protonated 4-ethoxymethylene-2-phenyl-2-oxazolin-5- one is also an oxazolone-type structure, while protonated cyclo-AG is a diketopiperazine structure. Soft-landing experiments were carried out to corroborate IRMPD results. Soft-landed protonated cyclo-AG and protonated 4-ethoxymethylene-2-phenyl-2- oxazolin-5-one underwent neutralization and retained their structures. The soft-landed b₂⁺ ion of AGG showed evidence of ring opening and conversion into a linear structure. The modified matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometers with SID capability were used to study fast dissociation kinetics (sub-microsecond dissociation). Silicon nanoparticle assisted laser desorption/ionization (SPALDI) allows the study of small molecule dissociation kinetics for ions without the matrix interference observed in MALDI. Well characterized systems, such as, N(CH₃)₄⁺, N(CD₃)₄⁺, and substituted benzylpyridinium ions were used to confirm reliability of the peak shape analysis. Obtained dissociation rates, of submicrosecond order, are consistent with the known dissociation theories. Dissociation of fullerenes, C₆₀ and C₇₀, was also investigated with the SID method using a fluorocarbon self-assembled monolayer (FSAM) surface. Fullerene ions produced C(2n)⁺ fragments ion in the kinetic energy range of 150-300 eV. At higher than 400 eV, mass spectra showed additional small fragment ions composed of odd numbers of C units. Energy resolved MS/MS curves support parallel dissociation at high SID energies while peak shape analysis explains sequential dissociation at about 150 eV range. Instrument modification of a MALDI-TOF mass spectrometer with SID capability allowed successful studies of fast unimolecular dissociation kinetics of small ions and fullerenes.