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Results for “kinetic mechanisms”
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Methanol Decomposition on Copper Surfaces under Ambient Conditions: Mechanism, Surface Kinetics, and Structure Sensitivity
Here, we study the adsorption of methanol vapor under ambient pressure and temperature conditions on low-index Cu surfaces using surface-sensitive infrared (IR) and X-ray spectroscopy techniques. The first step of methanol decomposition, i.e. , breaking of the O—H bond to form surface-bound methoxy, readily occurs under ambient conditions. Time-lapse IR spectra clearly indicate a gradually decreasing methoxy coverage, which does not obey well established kinetic models. We rationalize the initial temperature-independent, high, nonequilibrium coverage of methoxy by a H-bonded methanol assembly in the precursor state. A temperature-dependent equilibrium coverage is achieved as the excess methoxy is eliminated gradually via further dehydrogenation to CO that desorbs to the gas phase. The kinetics of this process displays a significant structure sensitivity with considerably faster kinetics on the Cu(110) surface compared to Cu(111) and Cu(100) surfaces.
Influence of Peptoid Sequence on the Mechanisms and Kinetics of 2D Assembly
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Kinetics and Mechanism of Fentanyl Dissociation from the μ-Opioid Receptor
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Tubulin islands containing slowly hydrolyzable GTP analogs regulate the mechanism and kinetics of microtubule depolymerization
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Experimental evidence of kinetically driven mechanisms for soot inception
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Probing photochemical kinetics and mechanisms using photoNMR
Nuclear magnetic resonance spectroscopy (NMR) is a form of spectroscopy that yields detailed mechanistic information about chemical structures, reactions, and processes. Photochemistry has widespread use across many industries and holds excellent utility for additive manufacturing (AM) processes. Here, we use photoNMR to investigate three photochemical processes spanning AM relevant timescales. We first investigate the photodecomposition of a photobase generator on the slow timescale, then the photoactivation of a ruthenium catalyst on the intermediate timescale, and finally the radical polymerization of an acrylate system on the fast timescale. In doing so, we gain fundamental insights to mission relevant photochemistries and develop a new spectroscopic capability at SNL.
Microstructural Coarsening Kinetics and Mechanical Property Changes in Long-term Aged Sn-Pb-Sb Solder Joints
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Research on the Mechanism and Kinetics of Oxidation of Silicon in Air Second Semiannual Report, 1 Dec. 1965 - 31 May 1966
Ellipsometer studies of oxide thin film growth on silicon in air
Research on the mechanism and kinetics of oxidation of silicon in air Semiannual report, 1 Jun. - 30 Nov. 1967
Ellipsometric measurements on refraction index of single silicon crystal with surface film
Research on the mechanism and kinetics of oxidation of silicon in air Semiannual report, 1 Dec. 1967 - 31 May 1968
Ellipsometric method for measuring optical parameters of substrate and oxidation surface layer thickness on silicon
Kinetics and mechanism of the thermal decomposition of nitronium perchlorate.
Nitronium perchlorate thermal decomposition under overpressure of He and O between 80 and 170 degrees noting weight loss processes and crystal phase change
Mechanism and kinetics of aging in Inconel 718
Age hardening in Inconel 718 is investigated using Brinell hardness measurements. Formation of a precipitate causes an increase in hardness.
Mechanisms and kinetics of cellulose fermentation for protein production
The development of a process (and ancillary processing and analytical techniques) to produce bacterial single-cell protein of good nutritional quality from waste cellulose is discussed. A fermentation pilot plant and laboratory were developed and have been in operation for about two years. Single-cell protein (SCP) can be produced from sugarcane bagasse--a typical agricultural cellulosic waste. The optimization and understanding of this process and its controlling variables are examined. Both batch and continuous fermentation runs have been made under controlled conditions in the 535 liter pilot plant vessel and in the laboratory 14-liter fermenters.
The kinetic and mechanical aspects of hydrogen-induced failure in metals
Premature hydrogen-induced failure observed to occur in many metal systems involves three stages of fracture: (1) crack initiation, (2) stable slow crack growth, and (3) unstable rapid crack growth. The presence of hydrogen at some critical location on the metal surface or within the metal lattice was shown to influence one or both of the first two stages of brittle fracture but has a negligible effect on the unstable rapid crack growth stage. The relative influence of the applied parameters of time, temperature, etc., on the propensity of a metal to exhibit hydrogen induced premature failure was investigated.
Zr partitioning and kinetics and mechanism
The results of investigations concerning the cooling histories of lunar rocks are reported. Publications resulting from this research are listed. Studies discussed include the partitioning of Zr between FeTi03 and Fe2Ti04 in the presence of Fe + Zr02, and ulvospinel reduction.
Kinetics and mechanisms of unimolecular gas-phase reactions of radical cations at times of 0.00001 to 10 microsec following field ionization
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