Application of carbon nanotubes (CNTs) in various fields demands a thorough investigation of their stability under irradiation. Open structure, ability to reorganize and heal defects, and large surface-to-volume ratio of carbon nanotubes affect materials' radiation response so that it differs from their bulk counterparts. Despite the work conducted to this date, radiation damage and mechanisms governing the evolution of CNTs under irradiation are still deficient in fundamental understanding. This dissertation is aimed to comprehend and characterize radiation response and crystalline-to-amorphous transition in ion and electron irradiated carbon nanotubes using various techniques, including but not limited to, transmission electron microscopy (TEM) and Raman spectroscopy. It shows that ion irradiation can be used to engineer properties of nanotubes in a controllable manner and significantly improve thermal diffusivity and conductivity of the material. This work also establishes the role of nuclear and electronic stopping powers in thermal diffusivity enhancement: thermal properties of irradiated CNTs are governed by nuclear stopping power of bombarding species. The change of thermal properties with irradiation is driven by two competing mechanisms: inter-tube displacement-mediated phonon transport and defect-induced phonon scattering. In addition to experiments, molecular dynamic simulations are used to confirm validity of the obtained results. Radiation damage in CNTs at various temperatures as a function of ion energy, flux and fluence is examined. Mechanisms governing crystalline-to-amorphous transition under electron and ion irradiations are explored, applicability of previously suggested models discussed, and new models introduced. The results show enhanced defect annealing at elevated irradiation temperatures, which delays the formation of amorphous regions. Investigation of nanotube stability after various processing techniques and irradiation indicated that radiation response of CNTs in a composite is similar to that of individual nanotubes.

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The structural properties of the group III-nitrides including AlN, Ga1-xMnxN, GaN:Cu, and InN were investigated by Raman spectroscopy. Absorption and photoluminescence spectroscopy were utilized to study the optical properties in these materials. The analysis of physical vapor transport grown AlN single crystals showed that oxygen, carbon, silicon, and boron are the major impurities in the bulk AlN. The Raman analysis revealed high crystalline quality and well oriented AlN single crystals. The absorption coefficient of AlN single crystals were assessed in the spectral range from deep UV to the FIR. The absorption and photoluminescence analysis indicate that, in addition to oxygen, carbon, boron, and silicon, contribute to the optical properties of bulk AlN crystals. In situ Cu-doped GaN epilayers with Cu concentrations in the range of 2x10^16 cm-3 - 5x1017 cm-3, grown on sapphire substrate by metal organic chemical vapor deposition, were investigated by Raman and PL spectroscopy. The Raman study revealed high crystalline GaN:Cu layers with minimal damage to the hexagonal lattice structure due to the Cu incorporation. A strong Cu related emission band at 2.4 eV was assigned to Cu induced optical transitions between deep Cu states and shallow residual donor states. Compensation of Cu states by residual donors and poor activation probability of deep Cu states are responsible for semi-insulating electrical conductivity. Ferromagnetic Ga1-xMnxN epilayers, grown by MOCVD with Mn concentration from x = 0 to x = 1.5, were optically investigated by Raman, PL, and transmission spectroscopy. The Raman studies revealed Mn-related Raman peaks at 300 cm-1, 609 cm-1, and 669 cm-1. Mn-related absorption and emission bands in Ga1-xMnxN were observed at 1.5 eV and 3.0 eV, respectively. The structural properties of InN layers, grown by high pressure-CVD with different free carrier concentrations, were analyzed by Raman spectroscopy. The Raman results show that the InN layers have high crystalline quality. The free carriers in layers were calculated by using the Lindhard-Mermin dielectric function taking into account finite wave vectors for various scattering processes including forbidden Frohlich, deformational potential associated with allowed electro-optic, and charge density fluctuation, mechanisms. The free carrier concentrations in the layers are below 1x10^20 cm-3.

As the critical dimensions of many devices, especially electronics, continue to become smaller, the ability to accurately analyze the properties at ever smaller scales becomes necessary. Optical techniques, such as confocal microscopy and various spectroscopies, have produced a wealth of information on larger length scales, above the diffraction limit. Scanning probe techniques, such as scanning tunneling microscopy and atomic force microscopy, provide information with an extremely fine resolution, often on the order of nanometers or angstroms. In this document, plasmon coupling is used to generate large signal increases, with clear future applications toward scanning probe optical spectroscopies. A variation on scanning tunneling microscopy is also used to study the surface structure of environmentally interesting nanoparticles. Traditional Raman spectroscopy is used to examine doped graphene, which is becoming a hot material for future electronic applications.

The fate and mobility of boric acid in the environment is largely controlled by adsorption reactions with soil organic matter and soil minerals to form surface complexes (Marzadori et al., 1991; Su and Suarez, 1995; Yermiyahu et al., 1995; Peak et al., 2002). The effects of humic acid (HA) and dissolved CO2 on boric acid adsorption on amorphous (am)-Al(OH)3 were investigated as their influence on sorption is potentially important. Although a model system was used in the studies, the findings should be generally useful to better understand the mobility and bioavailability of boric acid in the soil ecosystems.<p>In this dissertation, boric acid adsorption on pure am-Al(OH)3 and 5% w/w HA coated am-Al(OH)3 were investigated both as a function of pH (4.5 11) and initial boric acid concentration (0 4.5 mmol L-1). Batch adsorption isotherm experiments were also conducted with samples exposed to atmospheric CO2 and anaerobic (N2) conditions to examine the effects of dissolved CO2 on boric acid adsorption. Both the pH envelope and the adsorption isotherm experiments showed that the HA coating on am-Al(OH)3 and the presence of dissolved CO2 decreased boric acid adsorption. <p>Raman spectroscopy and boron (B) K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy were used to investigate the coordination of boric acid adsorbed at mineral/water interfaces. The Raman spectroscopy was less successful than expected as there were difficulties in identifying B bands in the 5% w/w HA coated am-Al(OH)3 samples.<p>The B K-edge XANES spectroscopy yielded better results. The XANES spectra of boric acid adsorption samples showed that both trigonal BO3 and tetrahedral BO4 coordinated complexes are present on the pure and HA coated mineral surfaces. At pH 7.0 and 9.2, the adsorption of boric acid on am-Al(OH)3 is predominantly inner-sphere trigonal complexes; with minor amounts of inner-sphere tetrahedral complexes. Both macroscopic and spectroscopic experiments revealed that the combination of HA coating on am-Al(OH)3 and dissolved CO2 decreased boric acid adsorption compared to adsorption on pure am-Al(OH)3.<p>The discoveries in this dissertation contribute significantly in understanding the effects of HA and dissolved CO2 has on boric acid adsorption in the environment. Since B speciation and the stability of am-Al(OH)3 mineral and HA changes with pH, the bioavailability of B is expected to change as well with pH. The adsorption on boric acid on am-Al(OH)3 and/or HA coated am-Al(OH)3 is expected to decrease the amount of boric acid available to plants. Therefore the nutrient management regimen will have to be modified for soils that are high in natural organic matter, carbonate and/or aluminum hydroxyl species.

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Following the concept utilize binary selenides as precursors with rapid thermal process (RTP) to fabricate CuInSe2 (CIS) thin film. In order to find the most promise process to get high quality CIS, several precursor stacking sequences have been tested which including SLG/In-Se/Cu-Se/Se, SLG/Cu-Se/In-Se/Se, SLG/0.1In-Se/Cu-Se/0.9/In-Se/Se, and SLG/0.5In-Se/Cu-Se/0.5/In-Se/Se, and the experiment result shows SLG/In-Se/Cu-Se/Se is the most suitable stacking sequence. Subsequently, varying Se flux to obtain several kinds copper selenides (Cu7Se4, Cu3Se2, CuSe, CuSe2) and indium selenides, try to find the suitable pairs through these binary selenides in SLG/In-Se/Cu-Se/Se structure. The suitable combination phase in Cu-Se precursor layer is CuSe blend with CuSe2. Large grain size CIS, about 1£gm, can be prepared in such precursor phase with film thickness between 700nm to 1£gm, strong (112) prefer-orientation vertical with substrate as well as good adhesion. Films were characterized through scanning election microscopy (SEM) to obtain grain size, surface morphology as well as film thickness. The X-ray diffractometer (XRD) was used to identify phase contained in whole film, and the phase constitution near surface layer was examined by Raman spectroscopy. If there are some second phases remaining in the thin film, combining the phase examination result of XRD and Raman spectroscopy, it can be estimate the second phase exist in the surface layers or internal film area.

This research has discussed the graphene growth mechanism and the achievement, the main purpose is to try the best method to grow graphene which is large size, uniform, and continue. The main issue is about growth and characterizations in full text which is separated by thermal annealing 6-H SiC(001) and chemical vapor deposition on the copper foil to grow graphenen. For instances, to adjust the growth parameters and the growth methods to get graphene and to control the quality, to analysis the number of layers, to research the characterizations during growth process, and to find the better transfer method are all the important focus in this paper. The morphology of samples is studied by SEM, AFM, STM, OM and so on, further the thickness of graphene layers can be observed by AFM and STM. Due to the limit of instruments, the thickness of graphene layer (~0.35 nm) and the thickness of 6-H SiC(001) steps (~1.5 nm) are not easy to observe actually. Raman spectroscopy is the main analysis tool I have employed, it is the fast way to calculate the number of layers (G, 2D band). In addition, Raman scattering is able to know the information of electronic structure variation (2D band), to investigate the stress which is caused by substrate and to estimate the quality of graphene (D, G band). Finally, I take chemical vapor deposition to grow graphenen on the copper foil. Sample is successfully transferred onto SiO2, and the number of graphene layers is estimated to be about two and the structure is AA stacking from these data. The data also shows the graphene is large size, uniform, and continue.

Uniform and aligned nanofibers have been obtained by eletrospinning. Activated carbon nanofibers (ACNFs) have been used as electrode materials for battery and electric double layer due to its porous properties. A high value of surface area can be attained (1000 - 3000 nm) by activation, due to the presence of micropores on the surface of nanofibers. A series of nanofibers have been prepared using different polymer precursors and concentrations by electrospinning in this study. Morphological study by SEM reveals a uniform and aligned fibrous structure for the PAN-based CNF (11 wt%) and a curved and twisted fibrous structure for the PAN-based CNF (8 wt%) and the acrylic-based CNF (9 wt%). Thus, the microstructure of CNF can be greatly influenced by the concentration of polymer precursor; high quality of nanofibers can be produced with higher polymer concentration and higher viscosity. The diameter of PAN-based nanofibers is gradually decreased from 400 to 200 nm during stabilization, carbonization, and activation, due mainly to the degradation and condensation. Surface of CNF becomes rough after activation due to the etching by potassium ions at high temperatures. Microstructural study by X-ray diffraction and Raman spectroscopy indicates a discernible diffraction peak at d002 = 0.356 nm and the ratio ID/IG = 1.83 of ACNFs, showing an amorphous and disordered structure, and leading to a low conductivity. Adsorption/desorption isotherms obtained from BET measurements under nitrogen atmosphere suggests a relatively small surface area of 8-10 m2/g, indicating that there might be no adsorption on the porous ACNF or the porous structure has been destroyed after carbonization. This leads to a relatively low conductance of 17 Faraday/g measured from the cyclic voltammetry.

Hemoglobin plays an important role in transporting oxygen in human beings and other mammals. Hemoglobin is a tetrameric protein composed of two alpha and two beta subunits. The £\ and £] subunits are both necessary and the stoichiometric ratio of the two dislike subunits is critical for hemoglobin to perform its oxygen-carrying function properly. To better understand the coupling between the £\ and £] subunits and the subunit disassembly pathway, p-hydroxymercuri-benzoate (PMB) has been used to react with the cysteine residues in hemoglobin. The hemoglobin tetramer becomes unstable and disassembles into £\ and £] subunits when the cysteine sites are perturbed upon reacting with PMB. There are three kinds of cysteine residues, £]93, £\104 and £]112, in human hemoglobin. The reactivity of different cysteine residues with PMB and their reaction sequence have been studied via the Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). The resonance Raman spectroscopy has been used to investigate the structural changes of hemoglobin accompanying the PMB-modification under the oxygenated and deoxygenated conditions. At last, a hemoglobin subunit disassembly mechanism is proposed and the site-specific roles of cysteine residues in human hemoglobin are discussed in detail.