The focus of this research is to explore the molecular-level interactions between reactive metal surfaces and aqueous environments by combined ultra-high vacuum/electrochemistry (UHV-EC) methodology. The objectives of this work are to understand (1) the effects of sulfate ions on the passivity of metal oxide/hydroxide surface layer, (2) the effects of sulfur-modification on the evolution of metal oxide/hydroxide surface layer, and (3) the effects of sulfur adsorbate on cation adsorption at metal surfaces.

Graphene receives enormous attention owing to its distinctive physical and chemical prosperities. Growing and transferring graphene to different substrates have been investigated. The graphene growing on the copper substrate has an advantage of low solubility of carbon on the copper which allow us to grow mostly monolayer graphene. Graphene sheet of few centimeters can be transferred to 300nm silicon oxide and quartz crystal pre-deposited with metal like Cu and Ru. Characterization of the graphene has been done with Raman and contact angle measurement and recently quartz crystal microbalance (QCM) has been employed. The underpotential deposition (UPD) process of Bi on Ru metal surface is studied using electrochemical quartz crystal microbalance (EQCM) and XPS techniques. Both Bi UPD and Bi bulk deposition are clearly observed on Ru in 1mM Bi (NO3)3/0.5M H2SO4. Bi monolayer coverage calculated from mass (MLMass) and from charge (MLCharge) were compared with respect to the potential scanning rates, anions and ambient controls. EQCM results indicate that Bi UPD on Ru is mostly scan rate independent but exhibits interesting difference at the slower scan. Bi UPD monolayer coverage calculated from cathodic frequency change (ΔfCathodic) is significantly smaller than the monolayer coverage derived from integrated charge under the cathodic …

We focused on a non-cooling room temperature microbolometer infrared imaging array device which includes a sensing layer of p-type a-Si:H component layers doped with boron. Boron incorporation and bonding configuration were investigated for a-Si:H films grown by plasma enhanced chemical deposition (PECVD) at varying substrate temperatures, hydrogen dilution of the silane precursor, and dopant to silane ratio using multiple internal reflection infrared spectroscopy (MIR-IR). This study was then confirmed from collaborators via Raman spectroscopy. MIR-IR analyses reveal an interesting counter-balance relationship between boron-doping and hydrogen-dilution growth parameters in PECVD-grown a-Si:H. Specifically, an increase in the hydrogen dilution ratio (H2/SiH4) or substrate temperature was found to increase organization of the silicon lattice in the amorphous films. It resulted in the decrease of the most stable SiH bonding configuration and thus decrease the organization of the film. The new chemical bonding information of a-Si:H thin film was correlated with the various boron doping mechanisms proposed by theoretical calculations. The study revealed the corrosion morphology progression on aluminum alloy (Al, 0.5% Cu) under acidic chloride solution. This is due to defects and a higher copper content at the grain boundary. Direct galvanic current measurement, linear sweep voltammetry (LSV), and Tafel plots are used …

An extremely facile and novel method called spontaneous deposition, to deposit noble metal nanoparticles on a most stable form of carbon (C) i.e. diamond is presented. Nanometer sized particles of such metals as platinum (Pt), palladium (Pd), gold (Au), copper (Cu) and silver (Ag) could be deposited on boron-doped (B-doped) polycrystalline diamond films grown on silicon (Si) substrates, by simply immersing the diamond/Si sample in hydrofluoric acid (HF) solution containing ions of the corresponding metal. The electrons for the reduction of metal ions came from the Si back substrate. The diamond/Si interfacial ohmic contact was of paramount importance to the observation of the spontaneous deposition process. The metal/diamond (M/C) surfaces were investigated using Raman spectroscopy, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and x-ray diffractometry (XRD). The morphology (i.e. size and distribution) of metal nanoparticles deposits could be controlled by adjusting the metal ion concentration, HF concentration and deposition time. XRD data indicate the presence of textured and strained crystal lattices of Pd for different Pd/C morphologies, which seem to influence the electrocatalytic oxidation of formaldehyde (HCHO). The sensitivity of electrocatalytic reactions to surface crystal structure implies that M/C could be fabricated for specific electrocatalytic applications. The research also …

The electrochemical quartz crystal microbalance (EQCM) has been proven an effective mean of monitoring up to nano-scale mass changes related to electrode potential variations at its surface. The principles of operation are based on the converse piezoelectric response of quartz crystals to mass variations on the crystal surface. In this work, principles and operations of the EQCM and piezo-electrodes are discussed. A conductive oxide, ruthenium oxide (RuO2) is a promising material to be used as a diffusion barrier for metal interconnects. Characterization of copper underpotential deposition (UPD) on ruthenium and RuO2 electrodes by means of electrochemical methods and other spectroscopic methods is presented. Copper electrodeposition in platinum and ruthenium substrates is investigated at pH values higher than zero. In pH=5 solutions, the rise in local pH caused by the reduction of oxygen leads to the formation of a precipitate, characterized as posnjakite or basic copper sulfate by means of X-ray electron spectroscopy and X-ray diffraction. The mechanism of formation is studied by means of the EQCM, presenting this technique as a powerful in-situ sensing device.

One objective of this study was to explore the intramolecular [2+2] cycloadditions of phenoxyketenes to carbonyl groups with isoflavones and benzofurans as target compounds. The other objective was to investigate the eyeloaddition reactions of rarely studied aminoketenes. The conversion of 2-(carboxyalkoxy)benzils to the corresponding phenoxyketenes leads to an intramolecular [2+2] cycloaddition to ultimately yield isoflavones and/or 3-aroylbenzofurans. The product distributions are dependent upon the substitution pattern in the original benzil acids. The initial cycloaddition products, β-lactones, are isolated in some instances while some β-lactones spontaneously underwent decarboxylation and could not be isolated. The ketene intermediate was demonstrated in the intramolecular reaction of benzil acids or ketoacids with sodium acetate and acetic anhydride. It is suggested that sodium acetate and acetic anhydride could serve as a source for the generation of ketenes directly from certain organic acids. The treatment of ketoacids with acetic anhydride and sodium acetate provides a simpler procedure to prepare benzofurans than going through the acid chloride with subsequent triethylamine dehydrochlorination to give the ketenes. N-Ary1-N-alkylaminoketenes were prepared for the first time from the corresponding glycine derivatives by using p-toluenesulfonyl chloride and triethylamine. These aminoketenes underwent in situ cycloadditions with cyclopentadiene, cycloheptene and cyclooctenes to yield only the …

Microwave spectroscopy is a gas phase technique typically geared toward measuring the rotational transitions of Molecules. The information contained in this type of spectroscopy pertains to a molecules structure, both geometric and electronic, which give insight into a molecule's chemistry. Typically this type of spectroscopy is high resolution, but narrowband ≤1 MHz in frequency. This is achieved by tuning a cavity, exciting a molecule with electromagnetic radiation in the microwave region, turning the electromagnetic radiation o, and measuring a signal from the molecular relaxation in the form of a free induction decay (FID). The FID is then Fourier transformed to give a frequency of the transition. "Fast passage" is defined as a sweeping of frequencies through a transition at a time much shorter (≤10 s) than the molecular relaxation (≈100 s). Recent advancements in technology have allowed for the creation of these fast frequency sweeps, known as "chirps", which allow for broadband capabilities. This work presents the design, construction, and implementation of one such novel, high-resolution microwave spectrometer with broadband capabilities. The manuscript also provides the theory, technique, and motivations behind building of such an instrument. In this manuscript it is demonstrated that, although a gas phase technique, solids, liquids, …

Modern three-dimensional integrated circuit design is rapidly evolving to more complex architecture. With continuous downscaling of devices, there is a pressing need for metrology tool development for rapid but efficient process and material characterization. In this dissertation work, application of a novel multiple internal reflection infrared spectroscopy metrology is discussed in various semiconductor fabrication process development. Firstly, chemical bonding structure of thin fluorocarbon polymer film deposited on patterned nanostructures was elucidated. Different functional groups were identified by specific derivatization reactions and model bonding configuration was proposed for the first time. In a continued effort, wet removal of these fluorocarbon polymer was investigated in presence of UV light. Mechanistic hypothesis for UV-assisted enhanced polymer cleaning efficiency was put forward supported by detailed theoretical consideration and experimental evidence. In another endeavor, plasma-induced damage to porous low-dielectric constant interlayer dielectric material was studied. Both qualitative and quantitative analyses of dielectric degradation in terms of increased silanol content and carbon depletion provided directions towards less aggressive plasma etch and strip process development. Infrared spectroscopy metrology was also utilized in surface functionalization evaluation of very thin organic films deposited by wet and dry chemistries. Palladium binding by surface amine groups was examined in plasma-polymerized amorphous …

Detection of ultratrace levels of metallic ion impurities in hydrofluoric acid solutions and alkaline hydrogen peroxide solution was demonstrated using a silicon-based sensing electrode. The sensor's operation principle is based on direct measurements of the silicon open-circuit potential shift generated by the interaction between metallic ions and the silicon-based sensing surface. The new sensor can have practical applications in the on-line monitoring of microelectronic chemical processing. The detection of Ag+ content in KODAK waste water was carried out successfully by this novel sensor. Trace levels of organic impurities in the hydrofluoric acid solutions and in the cleanroom air were characterized by multiple internal reflection infrared spectroscopy (MIRIS) using an organics probe prepared directly from a regular silicon wafer.

Methylglyoxal synthetase, which catalyzes the formation of methylglyoxal and inorganic phosphate from dihydroxyacetone phosphate, was found in extracts of Proteus vulgaris. An efficient purification procedure utilizing ion exchange column chromatography and isoelectric focusing has been developed. Homogeneity of the enzyme preparation was confirmed by polyacrylamide gel electrophoresis and rechromatography.Two components of methylglyoxal synthetase were obtained upon isoelectric focusing. A comparison of the chemical and physical properties of the two components was carried out. The enzyme is a dimer. In the presence of inorganic phosphate, the hyperbolic saturation kinetics with dihydroxyacetone phosphate are shifted to sigmoidal.

The distribution of isozymes of triosephosphate isomerase was normal in all human tissues examined. This finding argues against the existence of tissue-specific isozymes. Normal distributions of isozymes were also found in patients with cri-du-chat syndrome. Thus it is unlikely that a gene for triosephosphate isomerase is located on the short arm of chromosome five in man. When triosephosphate isomerases from a wide range of species were examined by starch gel electrophoresis, definite evolutionary patterns were found. Kinetic studies were conducted on human triosephosphate isomerase under conditions simulating the intracellular environment of the erythrocyte. Calculations using the kinetic parameters obtained indicate that even in triosephosphate isomerase deficiency disease, enough enzyme activity remains that the rate of glycolysis should not become inhibited.

The kinetics of the reaction of atomic sulfur and nitrogen dioxide have been investigated over the temperature range 298 to 650 K and pressures from 14 - 405 mbar using the laser flash photolysis - resonance fluorescence technique. The overall bimolecular rate expression k (T) = (1.88 ± 0.49) x10-11 exp-(4.14 ± 0.10 kJ mol-1)/RT cm3 molecule-1 s-1 is derived. Ab initio calculations were performed at the CCSD(T)/CBS level of theory and a potential energy surface has been derived. RRKM theory calculations were performed on the system. It is found that an initially formed SNO2 is vibrationally excited and the rate of collisional stabilization is slower than the rate of dissociation to SO + NO products by a factor of 100 - 1000, under the experimental conditions.

The oxidative elimination reactions of (5-X-phen)Mo(C0)₄ (X = H, CH₃, Cl, NO₂; phen = o-phenanthroline) and (3,4,7,8-(CH₃)₄-phen)Mo(CO)₄ with mercuric chloride in acetone have been investigated. In these reactions, a carbon monoxide group is replaced by two univalent ligands, accompanied by the corresponding increase in coordination number and formal oxidation state of the central metal atom, to give products of the type, (X-phen)Mo(CO)₃(Cl)HgCl. With the exception of (3,4,7,8-(CH₃)₄-phen), the substituted o-phenanthrolines were selected so as to minimize steric differences from one substrate to another while obtaining the widest range of pKₐ of the ligand.

Gas phase kinetics of the reactions involving hydroxyl radical and hydrogen atom were studied using experimental and ab initio theoretical techniques. The rate constant for the H + H2S reaction has been measured from 298 to 598 K by the laser photolysis/resonance fluorescence (LP-RF) technique. The transition state theory (TST) analysis coupled with the measurements support the suggestion that the reaction shows significant curvature in the Arrhenius plot. The LP-RF technique was also used to measure the rate constant of the H + CH3Br reaction over the temperature range 400-813 K. TST and density functional theory (DFT) calculations show that the dominant reaction channel is Br-abstraction. The reaction H + CF2=CF-CF=CF2 was first studied by flash photolysis/resonance fluorescence (FP-RF) method. The experiments of this work revealed distinctly non-Arrhenius behavior, which was interpreted in terms of a change in mechanism. DFT calculations suggest that the adduct is CF2H-CF•-CF=CF2. At lower temperatures a mixture of this molecule and CF2•-CFH-CF=CF2 is likely. The theoretical calculations show that H atom migrates in the fluoroethyl radicals through a bridging intermediate, and the barrier height for this process is lower in the less fluorinated ethyl radical. High level computations were also employed in studies of the …

The temperature dependence of the reactions of halogen atoms Cl and Br with SiH4 and (CH3)3SiH have been investigated with the flash photolysis-resonance fluorescence technique. CCI4 and CH2Br2 were used as precursors to produce Cl and Br atoms, respectively. Experiments gave {k(Cl + SiH4) (295 - 472 K)} = (1.56 +0.11) x 10-1 exp[(2.0 + 0.2) kJ mol'/RT] cm3 s4, {k(Br + SiH4)(295 - 575 K)} = (9.0 + 1.5) x 10-" exp[-(17.0 + 0.6) Id mol'/RT] cm3 s', {k(Cl + (CH3)3SiH)(295 - 468 K)} = (1.24 0.35) x 104 exp[(1.3 + 0.8) Id mol4/RT] cm3 s', and {k(Br + (CH3)3SiH)(295 - 456 K)} = (7.6 + 3.3) x 1010 exp[-(28.4 + 1.3) Id mol'/RT] cm3 s'. The results were compared with values from earlier work.

The substitution reaction of (DTN)W2 (CO)10 with P(OCH(CH3 )2 )3 is a stepwise reaction. The kinetics of step 1 follow the equation: -d[substrate] /dt = kld [substrate] + k la [substrate] [ligand]. Thus the mechanism of step 1 is expected to be a competition between dissociative and associative pathways. The kinetics of step 2 follow the equation: -d[(DTN)W(CO)5]/dt = k2dk3[(DTN)W(CO)5][ligand]/k-2[DTN] + k3[ligand] The plot of kobsd versus [ligand] thus is a hyperbolic curve and the plot of 1/kobsd versus 1/[L] exhibits linear behavior. A mechanism for step 2 in which (DTN)W(CO)5 dissociates to an intermediate, W(CO) 5 , and in which DTN and P(OCH(CH3 )2 )3 compete to associate with W(CO) 5 is favored. The dissociative rate constant of the first step, kld' is about 1.2 times of that of the second step, k2d. The dissociation of (DTN)W(CO) 5 from (DTN)W2 (CO) 1 0 is favored over the dissociation of DTN from (DTN)W(CO) 5 due to a combination of the steric, stoichiometric, charge repulsion and entropy effects of the reaction.

Certain ligand substitution reactions proceed to a complete displacement of the chelate ligand. Certain reactions proceed through a mechanism involving an initial fission of the tungsten-sulfur bond to afford a coordinatively-unsaturated intermediate which is rapidly attacked by chlorobenzene. The resulting solvated intermediate establishes an equilibrium which involves desolvation-solvation. Although main group organometallic chemistry has received a great deal of attention, this discussion will be centered in organotransition metal chemistry, in particular, metal carbonyls.

Pulsed laser flash photolysis with both visible and infrared detection has been applied to the study of the displacement of weakly coordinating ligands (Lw) by strongly "trapping" nucleophiles (Ls) containing either an olefinic functionality (Ls = 1-hexene, 1-decene, 1-tetradecene) or nitrogen (Ls = acetonitrile, hydrocinnamonitrile) from the photogenerated 16 electron pentacarbonylchromium (0) intermediate. 5-Chloropent-l-ene (Cl-ol), a potentially bidentate ligand, has been shown to form (ol-Cl) pentacarbonylchromium (0), in which Cl-ol is bonded to Cr via a lone pair on the chlorine, and isomerize to (Cl-ol) pentacarbonylchromium (0), in which Cl-ol is bonded to the olefinic functionality on the submillisecond time scale. This process has been studied in both the infrared and visible region employing both fluorobenzene or n-heptane as the "inert" diluent. Parallel studies employing 1-chlorobutane and 1-hexene were also evaluated and showed great similiarity with the Cl-ol system. The data supported a largely dissociative process with a possibility of a small interchange process involving the H's on the alkyl chain. Studies were also carried out for various Cr(CO)6/arene/Ls systems (arene = various alkyl or halogenated substituted benzenes). The data indicated that for both C6H5R (R=various alkyl chains) or multi-alkyl substituted arenes (i.e. o-xylene, 1,2,3-trimethylbenzene) containing an "unhindered" ring-edge, bonding …

Gas phase kinetics and thermochemistry of several halogenated species relevant to atmospheric, combustion and plasma chemistry were studied using experimental and ab initio theoretical techniques.

The kinetics of the reaction of atomic sulfur with acetylene (S (3P) + C2H2) were investigated experimentally via the flash photolysis resonance fluorescence method, and the theoretical potential energy surface for the reaction CN + SO was modeled via the density functional and configuration interaction computational methods. Sulfur is of interest in modern chemistry due to its relevance in combustion and atmospheric chemistry, in the Claus process, in soot and diamond-film formation and in astrochemistry. Experimental conditions ranged from 295 – 1015 K and 10 – 400 Torr of argon. Pressure-dependence was shown at all experimental temperatures. The room temperature high-pressure limit second order rate constant was (2.10 ± 0.08) × 10-13 cm3 molecule-1 s-1. The Arrhenius plot of the high-pressure limit rate constants gave an Ea of (11.34 ± 0.03) kJ mol-1 and a pre-exponential factor of (2.14 ± 0.19) × 10-11 cm3 molecule-1 s-1. S (3P) + C2H2 is likely an adduct forming reaction due to pressure-dependence (also supported by a statistical mechanics analysis) which involves intersystem crossing. The potential energy surface for CN + SO was calculated at the B3LYP/6-311G(d) level and refined at the QCISD/6-311G(d) level. The PES was compared to that of the analogous reaction …

Carbon nanotubes (CNT) have unparalleled mechanical properties, spanning several orders of magnitude over both length and time scales. Computational and experimental results vary greatly, partly due to the multitude of variables. Coupling physics-based molecular dynamics (MD) with informatics methodologies is proposed to navigate the large problem space. The adaptive intermolecular reactive empirical bond order (AIREBO) is used to model short range, long range and torsional interactions. A powerful approach that has not been used to study CNT mechanical properties is the derivation of descriptors and quantitative structure property relationships (QSPRs). For the study of defected single-walled CNTs (SWCNT), two descriptors were identified as critical: the density of non-sp2 hybridized carbons and the density of methyl groups functionalizing the surface. It is believed that both of these descriptors can be experimentally measured, paving the way for closed-loop computational-experimental development. Informatics can facilitate discovery of hidden knowledge. Further evaluation of the critical descriptors selected for Poisson’s ratio lead to the discovery that Poisson’s ratio has strain-varying nonlinear elastic behavior. CNT effectiveness in composites is based both on intrinsic mechanical properties and interfacial load transfer. In double-walled CNTs, inter-wall bonds are surface defects that decrease the intrinsic properties but also improve load transfer. …

Laser Ablation Inductively coupled plasma mass spectrometry (LA-ICP-MS) and Raman spectroscopy are both powerful imaging techniques. Their applications are numerous and extremely potential in the field of biology. In order to improve upon LA-ICP-MS an in-house built cold cell was developed and its effectiveness studied by imaging Brassica napus seeds. To further apply LA-ICP-MS and Raman imaging to the field of entomology a prong gilled mayfly (Ephemeroptera: Leptophlebiidae) from the Róbalo River, located on Navarino Island in Chile, was studied. Analysis of both samples showcased LA-ICP-MS and Raman spectroscopy as effective instruments for imaging trace elements and larger molecules in biological samples respectively.

A brief introduction to the current state of research in the Origins of Life field is given in Part I of this work. Part II covers original research performed by the author and co-workers. Layered Double Hydroxide (LDH) systems are anion-exchanging clays that have the general formula M(II)xM(III)(OH)(2x+2)Y, where M(II) and M(III) are any divalent and trivalent metals, respectively. Y can be nearly any anion, although modern naturally occuring LDH systems incorporate carbonate (CO32-), chloride (Cl-), or sulfate (SO42-) anions. Intercalated cobalticyanide anion shows a small yet observable deviation from local Oh symmetry causing small differences between its oriented and non-oriented infrared spectra. Nitroprusside is shown to intercalate into 2:1 Mg:Al LDH with decomposition to form intercalated ferrocyanide and nitrosyl groups of an unidentified nature. The [Ru(CN)6]4- anion is shown to intercalate into layered double hydroxides in the same manner as other hexacyano anions, such as ferrocyanide and cobalticyanide, with its three-fold rotational axis perpendicular to the hydroxide sheets. The square-planar tetracyano-nickelate(II), -palladate(II), and platinate(II) anions were intercalated into both 2:1 and 3:1 Mg:Al layered double hydroxides (LDH). The basal spacings in the 2:1 hosts are approximately 11 Å, indicating that the anions are inclined approximately 75 degrees relative to …

Layered double hydroxides (LDH) have been principally known as anion-exchanging, clay-like materials for several decades, and continues to be the main driving force for current and future research. The chemical interactions of LDH, with transition metallocyanides, have been a popular topic of investigation for many years, partly due to the use of powder x-ray diffraction and infrared spectroscopy as the main characterization tools. Each transition metallocyanide has a characteristic infrared stretching frequency that can be easily observed, and their respective sizes can be observed while intercalated within the interlayer of the LDH. The ability of LDH to incorporate metal cations or any ions/molecules/complexes, that have a postive charge, have not been previously investigated, mainly due to the chemical and physical nature of LDH. The possibility of cationic incorporation with LDH would most likely occur by surface adsorption, lattice metal replacement, or by intercalation into the LDH interlayers. Although infrared spectroscopy finds it main use through the identification of the anions incorporated with LDH, it can also be used to study and identify the various active and inactive bending and stretching modes that the metal hydroxide layers have.