147 Matching Results

Search Results

Advanced search parameters have been applied.

Heat of Combustion of the Product Formed by the Reaction of Acetylene, Ethylene, and Diborane

Description: "The net heat of combustion of the product formed by the reaction of diborane with a mixture of acetylene and ethylene was found to be 20,440 +/- 150 Btu per pound for the reaction of liquid fuel to gaseous carbon dioxide, gaseous water, and solid boric oxide. The measurements were made in a Parr oxygen-bomb calorimeter, and the combustion was believed to be 98 percent complete. The estimated net-heat of combustion for complete combustion would therefore be 20,850 +/- 150 Btu per pound" (p. 1).
Date: October 24, 1957
Creator: Tannenbaum, Stanley
Partner: UNT Libraries Government Documents Department

Numerical study of ethylene and acetylene laminar flame speeds

Description: Detailed chemical kinetic computations for ethylene-air and acetylene-air mixtures have been performed to simulate laminar flame speeds. Sensitivity analysis was applied to determine those reactions which strongly influence flame propagation. In ethylene-air mixtures, the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O reaction was one of the most sensitive reactions in the C{sub 2}H{sub 4}/C{sub 2}H{sub 3} submechanism and therefore this reaction was very important to ethylene flame propagation. This reaction was not considered in previously reported mechanisms used to model ethylene-air flame propagation. In acetylene-air mixtures, the C{sub 2}H{sub 2}+O {yields} Products, HCCO+H=CH{sub 2}(s)+CO, HCCO+O{sub 2}=CO{sub 2}+CO+H, H+C{sub 2}H{sub 2}(+M) = C{sub 2}H{sub 3}(+M) and CH{sub 2}(s)+C{sub 2}H{sub 2} = H{sub 2}CCCH+H were the most sensitive reactions in the C{sub 2}H{sub 2}/HCCO / CH{sub 2}(s) reaction set.
Date: March 1, 1995
Creator: Marinov, N.M.; Pitz, W.J. & Westbrook, C.K.
Partner: UNT Libraries Government Documents Department

Fundamental Flame Velocities of Pure Hydrocarbons 3: Extension of Tube Method of High Flame Velocities - Acetylene-Air Mixtures

Description: Memorandum presenting an extension of the tube method of measuring flame velocities to fundamental flame velocities of 141 centimeters per second. The extension was accomplished by reducing the flame-tube diameter from 25 to 12.5 millimeters. Results regarding the gas flow and spatial flame velocity, flame surface area, and fundamental flame velocity are provided.
Date: December 3, 1951
Creator: Levine, Oscar & Gerstein, Melvin
Partner: UNT Libraries Government Documents Department

Fragmentation pathwaysfor selected electronic states of theacetylene dication

Description: Coincident measurement of the Auger electron and fragmention momenta emitted after carbon core-level photoionization of acetylenehas yielded new understanding of how the dication fragments. Ab initiocalculations and experimental data, including body-frame Auger angulardistributions, are used to identify the parent electronic states andtogether yield a comprehensive map of the dissociation pathways whichinclude surface crossings and barriers to direct dissociation. The Augerangular distributions show evidence of core-holelocalization.
Date: December 18, 2007
Creator: Osipov, Timur; Rescigno, Thomas N.; Weber, Thorsten; Miyabe,Shungo; Jahnke, T.; Alnaser, A. et al.
Partner: UNT Libraries Government Documents Department

Spectroscopic and dynamical studies of highly energized small polyatomic molecules. Technical progress report, July 1, 1993--October 31, 1994

Description: This is a progress report on a project to spectroscopically study small polyatomic molecules which are highly excited. The authors describe work on acetylene (HCCH) and HCO. Their work involves dispersed fluorescence spectroscopy, and the development and application of superpolyad models for studying intramolecular vibrational redistribution.
Date: February 1, 1995
Creator: Field, R. W. & Silbey, R. J.
Partner: UNT Libraries Government Documents Department

The Synthesis and Reactivity of Bis(silyl)acetylenes

Description: Six bis(silyl)acetylenes with the following varied silicon substituents were prepared: I (Me, Me); II (H, H); III (Cl, H); IV (Cl, Cl); V (OMe, H); VI (OMe, OMe). While I and II may be prepared by the reaction of dilithio- or bis(bromomagnesium)-acetylide with appropriate chlorosilane, similar reactions designed to give III - VI give oligomers, YMe_2Si(C≡C-SiMe_2)_nY, VII, Y = Cl, OMe, as the major products indicating that the acetylenic functionality on silicon activates the chlorosilane toward nucleophilic substitution. Compounds III and IV were prepared by free radical chlorination of II. Methanolysis of III and IV gave quantitative yields of V and VI, respectively. In the presence of mineral acid, VI readily cyclized to give high yields of the cyclic siloxane octamethyl-4,9-dioxa-3,5,8,10-tetrasila-cyclodeca-1,6-diyne, VIII, and the analogous triyne, IX. It was determined that V and VI could be prepared directly from II in high yield by methanolysis with palladium catalyst. Vaska's complex also accomplished the conversion. I attempted to prepare bis(ethoxydimethylsilyl)acetylene by using of Wilkinson 's catalyst for hydrosilylation with acetaldehyde. The principal product of this reaction was 1-(dimethylsilyl)-3,5,5-trimethyl-4-oxa-3-silacyclopent-1-ene, XI.
Date: May 1987
Creator: Albanesi, Todd E. (Todd Edward)
Partner: UNT Libraries

Investigation of Structure and Properties of Low Temperature Deposited Diamond-Like Carbon Films

Description: Electrodeposition is a novel method for fabrication of diamond-like carbon (DLC) films on metal substrates. In this work, DLC was electrochemically deposited on different substrates based on an anodic oxidation cyclization of acetylene in liquid ammonia. Successfully anodic deposition was carried out for DLC onto nickel substrate at temperatures below -40°C. Comparative studies were performed on a series of different carbon sources (acetylene, sodium acetylide, and a mixture of acetylene and sodium acetylide). The films were characterized using a variety of methods including Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), XPS valence band spectra, and/or scanning electron microscopy (SEM). Raman spectroscopy is used as a bench mark technique to verify the presence of deposited DLC films, to access the films homogeneities, and to provide the ratio of the different carbon phases, mainly disordered graphite (D) and graphite (G) phases in the films. A combination of the Raman with FTIR and valence band spectra analysis allowed the distinction between hydrogenated DLC and unhydrogenated DLC films. Three different kinds of DLC [(1) hydrogenated DLC (a-C:H); (2) tetrahedral hydrogenated DLC (ta-C:H); and (3) graphitic-like DLC] were deposited depending upon the deposition conditions and substrates. Temperature and current density are the most important parameters to govern the quality of the deposited films, where adding of acetylide into the electrolyte led to films with a higher degree of graphitic phases. The proposed mechanism for acetylene anodic oxidation does not involve direct electron transfer but electrochemical cyclization of acetylene radical cations and hydrogen abstraction at the termination steps. Sodium acetylide, however, dissociates to an acetylenic ion, C2H-, in liquid ammonia. The electrochemistry heterogeneity also leads to island and two-dimensional (2D) nucleation growth of DLC films. Different bond formations of metal to carbon and different chemisorptions of acetylene on metal play important roles ...
Date: August 2004
Creator: Pingsuthiwong, Charoendee
Partner: UNT Libraries

Thermal Conversion of Methane to Acetylene

Description: This report describes the experimental demonstration of a process for the direct thermal conversion of methane to acetylene. The process utilizes a thermal plasma heat source to dissociation products react to form a mixture of acetylene and hydrogen. The use of a supersonic expansion of the hot gas is investigated as a method of rapidly cooling (quenching) the product stream to prevent further reaction or thermal decomposition of the acetylene which can lower the overall efficiency of the process.
Date: January 1, 2000
Creator: Fincke, James Russell; Anderson, Raymond Paul; Hyde, Timothy Allen; Wright, Randy Ben; Bewley, Randy Lee; Haggard, Delon C et al.
Partner: UNT Libraries Government Documents Department

Heats of Formation of Triplet Ethylene, Ethylidene, and Acetylene

Description: Heats of formation of the lowest triplet state of ethylene and the ground triplet state of ethylidene have been predicted by high level electronic structure calculations. Total atomization energies obtained from coupled-cluster CCSD(T) energies extrapolated to the complete basis set limit using correlation consistent basis sets (CBS), plus additional corrections predict the following heats of formation in kcal/mol: Delta H0f(C2H4,3A1) = 80.1 at 0 K and 78.5 at 298 K, and Delta H0f(CH3CH,3A") = 86.8 at 0 K and 85.1 at 298 K, with an error of less than +-1.0 kcal/mol. The vertical and adiabatic singlet-triplet separation energies of ethylene were calculated as Delta ES-T,vert = 104.1 and Delta ES-T,adia = 65.8 kcal/mol. These results are in excellent agreement with recent quantum Monte Carlo (DMC) values of 103.5 +- 0.3 and 66.4 +- 0.3 kcal/mol. Both sets of computational values differ from the experimental estimate of 58 +- 3 kcal/mol for the adiabatic splitting. The computed singlet-triplet gap at 0 K for acetylene is Delta ES-T,adia(C2H2) = 90.5 kcal/mol, which is in notable disagreement with the experimental value of 82.6 kcal/mol. The heat of formation of the triplet is Delta H0f(C2H2,3B2) = 145.3 kcal/mol. There is a systematic underestimation of the singlet-triplet gaps in recent photodecomposition experiments by ~;;7 to 8 kcal/mol. For vinylidene, we predict Delta H0f(H2CC,1A1) = 98.8 kcal/mol at 298 K (exptl. 100.3 +- 4.0), Delta H0f(H2CC,3B2) = 146.2 at 298 K, and an energy gap Delta ES-T-adia(H2CC) = 47.7 kcal/mol.
Date: June 28, 2007
Creator: Nguyen, M.T.; Matus, M.H.; Lester Jr, W.A. & Dixon, David A.
Partner: UNT Libraries Government Documents Department

Optimization of Acetylene Black Conductive Additive andPolyvinylidene Difluoride Composition for High Power RechargeableLithium-Ion Cells

Description: Fundamental electrochemical methods were applied to study the effect of the acetylene black (AB) and the polyvinylidene difluoride (PVDF) polymer binder on the performance of high-power designed rechargeable lithium ion cells. A systematic study of the AB/PVDF long-range electronic conductivity at different weight ratios is performed using four-probe direct current tests and the results reported. There is a wide range of AB/PVDF ratios that satisfy the long-range electronic conductivity requirement of the lithium-ion cathode electrode; however, a significant cell power performance improvement is observed at small AB/PVDF composition ratios that are far from the long-range conductivity optimum of 1 to 1.25. Electrochemical impedance spectroscopy (EIS) tests indicate that the interfacial impedance decreases significantly with increase in binder content. The hybrid power pulse characterization results agree with the EIS tests and also show improvement for cells with a high PVDF content. The AB to PVDF composition plays a significant role in the interfacial resistance. We believe the higher binder contents lead to a more cohesive conductive carbon particle network that results in better overall all local electronic conductivity on the active material surface and hence reduced charge transfer impedance.
Date: July 1, 2007
Creator: Liu, G.; Zheng, H.; Battaglia, V.S.; Simens, A.S.; Minor, A.M. & Song, X.
Partner: UNT Libraries Government Documents Department

The Breathing Orbital Valence Bond Method in Diffusion Monte Carlo: C-H Bond Dissociation ofAcetylene

Description: This study explores the use of breathing orbital valence bond (BOVB) trial wave functions for diffusion Monte Carlo (DMC). The approach is applied to the computation of the carbon-hydrogen (C-H) bond dissociation energy (BDE) of acetylene. DMC with BOVB trial wave functions yields a C-H BDE of 132.4 {+-} 0.9 kcal/mol, which is in excellent accord with the recommended experimental value of 132.8 {+-} 0.7 kcal/mol. These values are to be compared with DMC results obtained with single determinant trial wave functions, using Hartree-Fock orbitals (137.5 {+-} 0.5 kcal/mol) and local spin density (LDA) Kohn-Sham orbitals (135.6 {+-} 0.5 kcal/mol).
Date: May 30, 2008
Creator: Domin, D.; Braida, Benoit & Lester Jr., William A.
Partner: UNT Libraries Government Documents Department

In Situ Redox Manipulation Proof-of-Principle Test at the Fort Lewis Logistics Center: Final Report

Description: Pacific Northwest National Laboratory conducted a proof-of-principle test at the Fort Lewis Logistics Center to determine the feasibility of using the innovative remedial technology In Situ Redox Manipulation (ISRM) to treat groundwater contaminated with dissolved TCE. ISRM creates a permeable treatment zone in the subsurface to remediate redox-sensitive contaminants in groundwater. The permeable treatment zone is created by injecting a chemical reducing agent (sodium dithionite with pH buffers) into the aquifer through a well to chemically reduce the naturally occurring ferric iron in the sediments to ferrous iron. Once the reducing agent has been given sufficient time to react with aquifer sediments, residual chemicals and reaction products are withdrawn through the same well. Redox-sensitive contaminants such as TCE, moving in a dissolved-phase plume through the treatment zone, are destroyed. TCE is degraded via reductive dechlorination within the treatment zone to benign degradation products (acetylene, ehtylene). Analyses of sediment samples collected from post-test boreholes showed a high degree of iron reduction, which confirmed the effectiveness of the treatment zone.
Date: October 25, 2000
Creator: Vermeul, Vincent R.; Williams, Mark D.; Evans, John C.; Szecsody, James E.; Bjornstad, Bruce N. & Liikala, Terry L.
Partner: UNT Libraries Government Documents Department

The Effects of Various Conductive Additive and Polymeric Binder Contents on the Performance of a Lithium-ion Composite

Description: Fundamental electrochemical methods, cell performance tests, and physical characterization tests such as electron microscopy were used to study the effects of levels of the inert materials (acetylene black (AB), a nano-conductive additive, and polyvinylidene difluoride (PVDF), a polymer binder) on the power performance of lithium-ion composite cathodes. The electronic conductivity of the AB/PVDF composites at different compositions was measured with a four-point probe direct current method. The electronic conductivity was found to increase rapidly and plateau at a AB:PVDF ratio 0.2:1 (by weight), with 0.8:1 being the highest conductivity composition. AB:PVDF compositions along the plateau of 0.2:1, 0.4:1, 0.6:1 and 0.8:1 were investigated. Electrodes of each of those compositions were fabricated with different fractions of AB/PVDF to active material. It was found that at the 0.8:1 AB:PVDF, the rate performance improved with increases in the AB/PVDF loading, whereas at the 0.2:1 AB:PVDF, the rate performance improved with decreases in the AB/PVDF loading. The impedance of electrodes made with 0.6:1 AB:PVDF was low and relatively invariant.
Date: August 7, 2008
Creator: Stevenson, Cynthia; Liu, G.; Zheng, H.; Kim, S.; Deng, Y.; Minor, A.M. et al.
Partner: UNT Libraries Government Documents Department

Kinetic measurements on elementary fossil fuel combustion reactions over wide temperature ranges. Progress report, May 1, 1984--November 30, 1986

Description: The HTP (high-temperature photochemistry technique) has been used to study the reactions of ground state 0 atoms with C{sub 2}H{sub 4}, C{sub 2}H{sub 2}, H{sub 2} and D{sub 2} over the 300 to 1500 K temperature range. The results are described and discussed, as are the plans for study of the 0 + 1,3 butadiene and C{sub 2}H{sub 6} reactions in the remainder of the present grant period.
Date: December 1, 1986
Creator: Fontijn, A.; Mahmud, K. & Marshall, P.
Partner: UNT Libraries Government Documents Department

Synthesis, characterization and properties of rigid macromolecules with extended conjugation, using palladium-catalyzed alkynylated polyhaloarenes.

Description: A synthetic approach to macromolecules of acetylenic arrays and luminescent properties is proposed and the execution of initial steps is described. Palladium-catalyzed coupling of 1,3,5-triiodobenzene with trimethylsilylbuta-1,3-diyne, trimethylsilylocta-1,3,5,7-tetrayne, and trimethylsilylhexadeca-1,3,5,7,9,11,13,15-octayne to yield the new 1,3,5-tris(trimethylsilylbuta-1,3-diynyl)benzene and the proposed 1,3,5-tris(8-(trimethylsilyl)octa-1,3,5,7-tetraynyl)benzene and 1,3,5-tris(trimethylsilyl)hexadeca-1,3,5,7,9,11,13,15-octaynyl)benzene respectively. The proposed three-coordinate Au (I) complexed macromolecules will be derived from the metallation of the aforementioned alkynylated arenes.
Date: December 2007
Creator: Akintomide, Temiloluwa
Partner: UNT Libraries

A scaling theory for the assignment of spectra in the irregular region. Continuation progress report

Description: The ultimate object of our program is to learn how to extract information about molecular rovibrational motions from experimental spectra or calculated energy levels. This goal of spectroscopy and theoretical chemistry has historically only been possible in the regular spectral region. Our project is one of several which are aimed at spectral interpretation in the chaotic or mixed chaotic plus regular regions. Our particular tools involve a scaling theory developed under our previous DOE support period. This theory uses experimentally fitted spectral Hamiltonians or Hamiltonian`s whose potentials are calculated using quantum chemistry, to obtain energy levels as a function of h{sup -1}. The scaling theory then uses this input to highlight the actions of the subset of all periodic orbits which control the dynamics at any given energy up to dissociation. The periodic orbits themselves, are the skeleton of classical phase space for the molecular motions and are found by classical non-linear dynamic techniques. The finding and following of these periodic orbits by constructing a bifurcation diagram, and in 2D, Poincare surfaces of section, is labor intensive and takes much of our available man hours. We have two projects, {open_quotes}acetylene{close_quotes} and {open_quotes}NO{sub 2}.{close_quotes} Below we first briefly sketch the results of the classical phase space study using the fitted spectral Hamiltonian that describes pure bending dynamics of in the acetylene X{sup 1}{Sigma}{sub g}{sup +} state to 15,000 cm{sup -1} of internal energy. The work on NO{sub 2} will follow. The specific purpose of this part of our work is to establish relations between experimental data and quantum mechanical results on one side and the behaviour of the dynamics given by the corresponding classical Hamiltonian function on the other side for the bend vibrations of the C{sub 2}H{sub 2} molecule. We transform it into a classical Hamiltonian function given in action ...
Date: June 1, 1998
Creator: Taylor, H.S.
Partner: UNT Libraries Government Documents Department

Theoretical studies of combustion dynamics. Final progress report, August 1, 1986--July 31, 1997

Description: The authors completed a number of projects during this period of time. This resulted in fifty nine publications, which are listed below. The major thrusts of this research are the development and application of quantum methods to the study of fundamental chemical processes of importance in gas-phase combustion. Broadly speaking the work falls into two categories. One is the development and application of reduced dimensionality theories of chemical reactions, and the other into studies of radical-radical reactions that proceed mainly via complex formation. The various projects in these two areas and their intersection are reviewed.
Date: March 1, 1998
Creator: Bowman, J.M.
Partner: UNT Libraries Government Documents Department

Infrared absorption measurements of the kinetics of Cl atom reactions with C{sub 3}H{sub n} (n=4,6) unsaturated hydrocarbons between 300-850 K

Description: The reaction of chlorine (Cl) atoms with the unsaturated C{sub 3}H{sub n} where n=4,6, hydrocarbons propylene, allene, and methyl acetylene have been uninvestigated as a function of temperature and pressure.
Date: August 1, 1997
Creator: Farrell, J.T.; Pilgrim, J.S. & Taatjes, C.A.
Partner: UNT Libraries Government Documents Department