THERMAL PERFORMANCE ANALYSIS FOR SMALL ION-EXCHANGE CESIUM REMOVAL PROCESS (open access)

THERMAL PERFORMANCE ANALYSIS FOR SMALL ION-EXCHANGE CESIUM REMOVAL PROCESS

The In-Riser Ion Exchange program focuses on the development of in-tank systems to decontaminate high level waste (HLW) salt solutions at the Savannah River Site (SRS) and the Hanford Site. Small Column Ion Exchange (SCIX) treatment for cesium removal is a primary in-riser technology for decontamination prior to final waste immobilization in Saltstone. Through this process, radioactive cesium from the salt solution is adsorbed onto the ion exchange media which is packed within a flow-through column. Spherical Resorcinol-Formaldehyde (RF) is being considered as the ion exchange media for the application of this technology at both sites. A packed column loaded with media containing radioactive cesium generates significant heat from radiolytic decay. Under normal operating conditions, process fluid flow through the column can provide adequate heat removal from the columns. However, in the unexpected event of loss of fluid flow or fluid drainage from the column, the design must be adequate to handle the thermal load to avoid unacceptable temperature excursions. Otherwise, hot spots may develop locally which could degrade the performance of the ion-exchange media or the temperature could rise above column safety limits. Data exists which indicates that performance degradation with regard to cesium removal occurs with RF at …
Date: December 29, 2009
Creator: Lee, S. & King, W.
Object Type: Article
System: The UNT Digital Library
The Underground Test Area Project of the Nevada Test Site: Building Confidence in Groundwater Flow and Transport Models at Pahute Mesa Through Focused Characterization Studies (open access)

The Underground Test Area Project of the Nevada Test Site: Building Confidence in Groundwater Flow and Transport Models at Pahute Mesa Through Focused Characterization Studies

Pahute Mesa at the Nevada Test Site contains about 8.0E+07 curies of radioactivity caused by underground nuclear testing. The Underground Test Area Subproject has entered Phase II of data acquisition, analysis, and modeling to determine the risk to receptors from radioactivity in the groundwater, establish a groundwater monitoring network, and provide regulatory closure. Evaluation of radionuclide contamination at Pahute Mesa is particularly difficult due to the complex stratigraphy and structure caused by multiple calderas in the Southwestern Nevada Volcanic Field and overprinting of Basin and Range faulting. Included in overall Phase II goals is the need to reduce the uncertainty and improve confidence in modeling results. New characterization efforts are underway, and results from the first year of a three-year well drilling plan are presented.
Date: December 29, 2009
Creator: Pawloski, G A; Wurtz, J & Drellack, S L
Object Type: Article
System: The UNT Digital Library
2009 Pilot Scale Fluidized Bed Steam Reforming Testing Using the Thor (Thermal Organic Reduction) Process: Analytical Results for Tank 48h Organic Destruction - 10408 (open access)

2009 Pilot Scale Fluidized Bed Steam Reforming Testing Using the Thor (Thermal Organic Reduction) Process: Analytical Results for Tank 48h Organic Destruction - 10408

The Savannah River Site (SRS) must empty the contents of Tank 48H, a 1.3 million gallon Type IIIA HLW storage tank, to return this tank to service. The tank contains organic compounds, mainly potassium tetraphenylborate that cannot be processed downstream until the organic components are destroyed. The THOR{reg_sign} Treatment Technologies (TTT) Fluidized Bed Steam Reforming (FBSR) technology, herein after referred to as steam reforming, has been demonstrated to be a viable process to remove greater than 99.9% of the organics from Tank 48H during various bench scale and pilot scale tests. These demonstrations were supported by Savannah River Remediation (SRR) and the Department of Energy (DOE) has concurred with the SRR recommendation to proceed with the deployment of the FBSR technology to treat the contents of Tank 48H. The Savannah River National Laboratory (SRNL) developed and proved the concept with non-radioactive simulants for SRR beginning in 2003. By 2008, several pilot scale campaigns had been completed and extensive crucible testing and bench scale testing were performed in the SRNL Shielded Cells using Tank 48H radioactive sample. SRNL developed a Tank 48H non-radioactive simulant complete with organic compounds, salt, and metals characteristic of those measured in a sample of the radioactive …
Date: December 28, 2009
Creator: Williams, M. R.; Jantzen, Carol M.; Burket, P. R.; Crawford, C. L.; Daniel, W. E.; Aponte, C. et al.
Object Type: Article
System: The UNT Digital Library
Final Technical Report (open access)

Final Technical Report

The Center of Excellence for Hazardous Materials Management award was used to establish the organization and initiate investigations of hazardous waste issues along the U.S.-Mexico border. Scientific investigations conducted during the execution of this grant contributed significant data and established new sampling protocols to the dimension, frequency and severity of hazardous materials (e.g., heavy metals) along the U.S.-Mexico border. Additionally, new protocols and assessments with distinct Homeland Security implications were embedded thus establishing a baseline that will be significant for related investigations in the future.
Date: December 28, 2009
Creator: Lynn, Douglas C. & Restani, Marco, Ph.D
Object Type: Report
System: The UNT Digital Library
SECONDARY WASTE/ETF (EFFLUENT TREATMENT FACILITY) PRELIMINARY PRE-CONCEPTUAL ENGINEERING STUDY (open access)

SECONDARY WASTE/ETF (EFFLUENT TREATMENT FACILITY) PRELIMINARY PRE-CONCEPTUAL ENGINEERING STUDY

This pre-conceptual engineering study is intended to assist in supporting the critical decision (CD) 0 milestone by providing a basis for the justification of mission need (JMN) for the handling and disposal of liquid effluents. The ETF baseline strategy, to accommodate (WTP) requirements, calls for a solidification treatment unit (STU) to be added to the ETF to provide the needed additional processing capability. This STU is to process the ETF evaporator concentrate into a cement-based waste form. The cementitious waste will be cast into blocks for curing, storage, and disposal. Tis pre-conceptual engineering study explores this baseline strategy, in addition to other potential alternatives, for meeting the ETF future mission needs. Within each reviewed case study, a technical and facility description is outlined, along with a preliminary cost analysis and the associated risks and benefits.
Date: December 28, 2009
Creator: May, Thomas H.; Gehner, Phillip D.; Stegen, Gary; Hymas, Jay; Pajunen, Al; Sexton, Rich et al.
Object Type: Report
System: The UNT Digital Library
Survival Rates of Juvenile Salmonids Passing Through the Bonneville Dam and Spillway in 2008 (open access)

Survival Rates of Juvenile Salmonids Passing Through the Bonneville Dam and Spillway in 2008

This report describes a 2008 acoustic telemetry survival study conducted by the Pacific Northwest National Laboratory for the Portland District of the U.S. Army Corps of Engineers. The study estimated the survival of juvenile Chinook salmon and steelhead passing Bonneville Dam (BON) and its spillway. Of particular interest was the relative survival of smolts detected passing through end spill bays 1-3 and 16-18, which had deep flow deflectors immediately downstream of spill gates, versus survival of smolts passing middle spill bays 4-15, which had shallow flow deflectors.
Date: December 28, 2009
Creator: Ploskey, Gene R.; Weiland, Mark A.; Faber, Derrek M.; Deng, Zhiqun; Johnson, Gary E.; Hughes, James S. et al.
Object Type: Report
System: The UNT Digital Library
Systems Analysis of an Advanced Nuclear Fuel Cycle Based on a Modified UREX+3c Process (open access)

Systems Analysis of an Advanced Nuclear Fuel Cycle Based on a Modified UREX+3c Process

The research described in this report was performed under a grant from the U.S. Department of Energy (DOE) to describe and compare the merits of two advanced alternative nuclear fuel cycles -- named by this study as the “UREX+3c fuel cycle” and the “Alternative Fuel Cycle” (AFC). Both fuel cycles were assumed to support 100 1,000 MWe light water reactor (LWR) nuclear power plants operating over the period 2020 through 2100, and the fast reactors (FRs) necessary to burn the plutonium and minor actinides generated by the LWRs. Reprocessing in both fuel cycles is assumed to be based on the UREX+3c process reported in earlier work by the DOE. Conceptually, the UREX+3c process provides nearly complete separation of the various components of spent nuclear fuel in order to enable recycle of reusable nuclear materials, and the storage, conversion, transmutation and/or disposal of other recovered components. Output of the process contains substantially all of the plutonium, which is recovered as a 5:1 uranium/plutonium mixture, in order to discourage plutonium diversion. Mixed oxide (MOX) fuel for recycle in LWRs is made using this 5:1 U/Pu mixture plus appropriate makeup uranium. A second process output contains all of the recovered uranium except the …
Date: December 28, 2009
Creator: Johnson, E. R. & Best, R. E.
Object Type: Report
System: The UNT Digital Library
Worker Environment Beryllium Characterization Study (open access)

Worker Environment Beryllium Characterization Study

This report summarizes the conclusion of regular monitoring of occupied buildings at the Nevada Test Site and North Las Vegas facility to determine the extent of beryllium (Be) contamination in accordance with Judgment of Needs 6 of the August 14, 2003, “Minnema Report.”
Date: December 28, 2009
Creator: NSTec Environment, Safety, Health & Quality
Object Type: Report
System: The UNT Digital Library
Formation of inner-shell autoionizing CO+ states below the CO++ threshold (open access)

Formation of inner-shell autoionizing CO+ states below the CO++ threshold

We report a kinematically complete experiment on the production of CO{sup +} autoionizing states following photoionization of carbon monoxide below its vertical double ionization threshold. Momentum imaging spectroscopy is used to measure the energies and body-frame angular distributions of both photo- and autoionization electrons, as well as the kinetic energy release (KER) of the atomic ions. This data, in combination with ab initio theoretical calculations, provides insight into the nature of the cation states produced and their subsequent dissociation into autoionizing atomic (O*) fragments.
Date: December 27, 2009
Creator: Osipov, Timur; Weber, Thorsten; Rescigno, Thomas N; Lee, Sun; Orel, Ann; Schoffler, Markus et al.
Object Type: Article
System: The UNT Digital Library
Institute for Multiscale Modeling of Biological Interactions (open access)

Institute for Multiscale Modeling of Biological Interactions

The Institute for Multiscale Modeling of Biological Interactions (IMMBI) has two primary goals: Foster interdisciplinary collaborations among faculty and their research laboratories that will lead to novel applications of multiscale simulation and modeling methods in the biological sciences and engineering; and Building on the unique biophysical/biology-based engineering foundations of the participating faculty, train scientists and engineers to apply computational methods that collectively span multiple time and length scales of biological organization. The success of IMMBI will be defined by the following: Size and quality of the applicant pool for pre-doctoral and post-doctoral fellows; Academic performance; Quality of the pre-doctoral and post-doctoral research; Impact of the research broadly and to the DOE (ASCR program) mission; Distinction of the next career step for pre-doctoral and post-doctoral fellows; and Faculty collaborations that result from IMMBI activities. Specific details about accomplishments during the three years of DOE support for IMMBI have been documented in Annual Progress Reports (April 2005, June 2006, and March 2007) and a Report for a National Academy of Sciences Review (October 2005) that were submitted to DOE on the dates indicated. An overview of these accomplishments is provided.
Date: December 26, 2009
Creator: Paulaitis, Michael E.; Garcia-Moreno, Bertrand & Lenhoff, Abraham
Object Type: Report
System: The UNT Digital Library
Optical People Counting for Demand Controlled Ventilation: A Pilot Study of Counter Performance (open access)

Optical People Counting for Demand Controlled Ventilation: A Pilot Study of Counter Performance

This pilot scale study evaluated the counting accuracy of two people counting systems that could be used in demand controlled ventilation systems to provide control signals for modulating outdoor air ventilation rates. The evaluations included controlled challenges of the people counting systems using pre-planned movements of occupants through doorways and evaluations of counting accuracies when naive occupants (i.e., occupants unaware of the counting systems) passed through the entrance doors of the building or room. The two people counting systems had high counting accuracy accuracies, with errors typically less than 10percent, for typical non-demanding counting events. However, counting errors were high in some highly challenging situations, such as multiple people passing simultaneously through a door. Counting errors, for at least one system, can be very high if people stand in the field of view of the sensor. Both counting system have limitations and would need to be used only at appropriate sites and where the demanding situations that led to counting errors were rare.
Date: December 26, 2009
Creator: Fisk, William J. & Sullivan, Douglas
Object Type: Report
System: The UNT Digital Library
1-D Van der Waals Foams Heated by Ion Beam Energy Deposition (open access)

1-D Van der Waals Foams Heated by Ion Beam Energy Deposition

One dimensional simulations of various initial average density aluminum foams (modeled as slabs of solid metal separated by low density regions) heated by volumetric energy deposition are conducted with a Lagrangian hydrodynamics code using a van der Waals equation of tate (EOS). The resulting behavior is studied to facilitate the design of future warm dense matter (WDM) experiments at LBNL. In the simulations the energy deposition ranges from 10 to 30 kJ/g and from 0.075 to 4.0 ns total pulse length, resulting in temperatures from approximately 1 o 4 eV. We study peak pressures and temperatures in the foams, expansion velocity, and the phase evolution. Five relevant time scales in the problem are identified. Additionally, we present a method for characterizing the level of inhomogeneity in a foam target as it is heated and the time it takes for a foam to homogenize.
Date: December 23, 2009
Creator: Zylstra, A. B.; Barnard, J. J. & More, R. M.
Object Type: Article
System: The UNT Digital Library
Continuity and Performance in Composite Electrodes (open access)

Continuity and Performance in Composite Electrodes

It is shown that the rate performance of a lithium battery composite electrode may be compromised by poor internal connectivity due to defects and inhomogeneities introduced during electrode fabrication or subsequent handling. Application of a thin conductive coating to the top surface of the electrode or to the separator surface in contact with the electrode improves the performance by providing alternative current paths to partially isolated particles of electroactive material. Mechanistic implications are discussed and strategies for improvement in electrode design and fabrication are presented.
Date: December 23, 2009
Creator: Chen, Guoying & Richardson, Thomas J.
Object Type: Article
System: The UNT Digital Library
Pretreatment Engineering Platform Phase 1 Final Test Report (open access)

Pretreatment Engineering Platform Phase 1 Final Test Report

Pacific Northwest National Laboratory (PNNL) was tasked by Bechtel National Inc. (BNI) on the River Protection Project, Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to conduct testing to demonstrate the performance of the WTP Pretreatment Facility (PTF) leaching and ultrafiltration processes at an engineering-scale. In addition to the demonstration, the testing was to address specific technical issues identified in Issue Response Plan for Implementation of External Flowsheet Review Team (EFRT) Recommendations - M12, Undemonstrated Leaching Processes.( ) Testing was conducted in a 1/4.5-scale mock-up of the PTF ultrafiltration system, the Pretreatment Engineering Platform (PEP). Parallel laboratory testing was conducted in various PNNL laboratories to allow direct comparison of process performance at an engineering-scale and a laboratory-scale. This report presents and discusses the results of those tests.
Date: December 23, 2009
Creator: Kurath, Dean E.; Hanson, Brady D.; Minette, Michael J.; Baldwin, David L.; Rapko, Brian M.; Mahoney, Lenna A. et al.
Object Type: Report
System: The UNT Digital Library
Reactions of the CN Radical with Benzene and Toluene: Product Detection and Low-Temperature Kinetics (open access)

Reactions of the CN Radical with Benzene and Toluene: Product Detection and Low-Temperature Kinetics

Low temperature rate coefficients are measured for the CN + benzene and CN + toluene reactions using the pulsed Laval nozzle expansion technique coupled with laser-induced fluorescence detection. The CN + benzene reaction rate coefficient at 105, 165 and 295 K is found to be relatively constant over this temperature range, 3.9 - 4.9 x 10-10 cm3 molecule-1 s-1. These rapid kinetics, along with the observed negligible temperature dependence, are consistent with a barrierless reaction entrance channel and reaction efficiencies approaching unity. The CN + toluene reaction is measured to have a slower rate coefficient of 1.3 x 10-10 cm3 molecule-1 s-1 at 105 K. At room temperature, non-exponential decay profiles are observed for this reaction that may suggest significant back-dissociation of intermediate complexes. In separate experiments, the products of these reactions are probed at room temperature using synchrotron VUV photoionization mass spectrometry. For CN + benzene, cyanobenzene (C6H5CN) is the only product recorded with no detectable evidence for a C6H5 + HCN product channel. In the case of CN + toluene, cyanotoluene (NCC6H4CH3) constitutes the only detected product. It is not possible to differentiate among the ortho, meta and para isomers of cyanotoluene because of their similar ionization energies …
Date: December 23, 2009
Creator: Trevitt, Adam J.; Goulay, Fabien; Taatjes, Craig A.; Osborn, David L. & Leone, Stephen R.
Object Type: Article
System: The UNT Digital Library
Role for DNA methylation in the regulation of miR-200c and miR-141 expression in normal and cancer cells (open access)

Role for DNA methylation in the regulation of miR-200c and miR-141 expression in normal and cancer cells

BACKGROUND: The microRNA-200 family participates in the maintenance of an epithelial phenotype and loss of its expression can result in epithelial to mesenchymal transition (EMT). Furthermore, the loss of expression of miR-200 family members is linked to an aggressive cancer phenotype. Regulation of the miR-200 family expression in normal and cancer cells is not fully understood. METHODOLOGY/ PRINCIPAL FINDINGS: Epigenetic mechanisms participate in the control of miR-200c and miR-141 expression in both normal and cancer cells. A CpG island near the predicted mir-200c/mir-141 transcription start site shows a striking correlation between miR-200c and miR-141 expression and DNA methylation in both normal and cancer cells, as determined by MassARRAY technology. The CpG island is unmethylated in human miR-200/miR-141 expressing epithelial cells and in miR-200c/miR-141 positive tumor cells. The CpG island is heavily methylated in human miR-200c/miR-141 negative fibroblasts and miR-200c/miR-141 negative tumor cells. Mouse cells show a similar inverse correlation between DNA methylation and miR-200c expression. Enrichment of permissive histone modifications, H3 acetylation and H3K4 trimethylation, is seen in normal miR-200c/miR-141-positive epithelial cells, as determined by chromatin immunoprecipitation coupled to real-time PCR. In contrast, repressive H3K9 dimethylation marks are present in normal miR-200c/miR-141-negative fibroblasts and miR-200c/miR-141 negative cancer cells and the …
Date: December 23, 2009
Creator: Vrba, Lukas; Jensen, Taylor J.; Garbe, James C.; Heimark, Ronald L.; Cress, Anne E.; Dickinson, Sally et al.
Object Type: Article
System: The UNT Digital Library
Triangulation Made Easy (open access)

Triangulation Made Easy

We describe a simple and efficient algorithm for two-view triangulation of 3D points from approximate 2D matches based on minimizing the L2 reprojection error. Our iterative algorithm improves on the one by Kanatani et al. by ensuring that in each iteration the epipolar constraint is satisfied. In the case where the two cameras are pointed in the same direction, the method provably converges to an optimal solution in exactly two iterations. For more general camera poses, two iterations are sufficient to achieve convergence to machine precision, which we exploit to devise a fast, non-iterative method. The resulting algorithm amounts to little more than solving a quadratic equation, and involves a fixed, small number of simple matrixvector operations and no conditional branches. We demonstrate that the method computes solutions that agree to very high precision with those of Hartley and Sturm's original polynomial method, though achieves higher numerical stability and 1-4 orders of magnitude greater speed.
Date: December 23, 2009
Creator: Lindstrom, P.
Object Type: Article
System: The UNT Digital Library
Apple Strength Issues (open access)

Apple Strength Issues

Strength of the apple parts has been noticed to decrease, especially those installed by the new induction heating system since the LEP campaign started. Fig. 1 shows the ultimate tensile strength (UTS), yield strength (YS), and elongation of the installed or installation-simulated apples on various systems. One can clearly see the mean values of UTS and YS of the post-LEP parts decreased by about 8 ksi and 6 ksi respectively from those of the pre-LEP parts. The slight increase in elongation seen in Fig.1 can be understood from the weak inverse relationship between the strength and elongation in metals. Fig.2 shows the weak correlation between the YS and elongation of the parts listed in Fig. 1. Strength data listed in Figure 1 were re-plotted as histograms in Figs. 3 and 4. Figs. 3a and 4a show histograms of all UTS and YS data. Figs. 3b and 4b shows histograms of pre-LEP data and Figs. 3c and 4c of post-LEP data. Data on statistical scatter of tensile strengths have been rarely published by material suppliers. Instead, only the minimum 'guaranteed' strength data are typically presented. An example of strength distribution of aluminum 7075-T6 sheet material, listed in Fig. 5, show that …
Date: December 22, 2009
Creator: Syn, C.
Object Type: Report
System: The UNT Digital Library
ATLAS Note ATL-COM-PHYS-2009. (open access)

ATLAS Note ATL-COM-PHYS-2009.

The program InvMass has been developed to perform a general model-independent search for new particles using the ATLAS detector at the Large Hadron Collider (LHC), a proton-proton collider at CERN. The search is performed by examining statistically significant variations from the Standard Model predictions in exclusive event classes classified according to the number of identified objects. The program, called InvMass, finds all relevant particle groups identified with the ATLAS detector and analyzes their production rates, invariant masses and the total transverse momenta. The generic code of InvMass can easily be adapted for any particle types identified with the ATLAS detector. Several benchmark tests are presented.
Date: December 22, 2009
Creator: Chekanov, S. & Boomsma, J.
Object Type: Report
System: The UNT Digital Library
Development of Polarized Photocathodes for the Linear Collider (open access)

Development of Polarized Photocathodes for the Linear Collider

In prior years a Wisconsin-SLAC collaboration developed polarized photocathodes which were used for the SLAC SLD and fixed target programs. Currently, the R&D program goal is the development of a polarized electron source (PES) which meets the ILC requirements for polarization, charge, lifetime, and pulse structure. There are two parts to this program. One part is the continued improvement of photocathode structures with higher polarization. The second part is the design and development of the laser system used to drive the photocathode. The long pulse train for the ILC introduces new challenges for the PES. More reliable and stable operation of the PES may be achievable if appropriate R&D is carried out for higher voltage operation and for a simpler photocathode load-lock system. The collaboration with SLAC is through the Polarized Photocathode Research Collaboration (PPRC). Senior SLAC personnel include T. Maruyama, J. Clendenin, R. Kirby, and A. Brachmann.
Date: December 22, 2009
Creator: Prepost, Richard
Object Type: Report
System: The UNT Digital Library
Extreme Scaling of Production Visualization Software on Diverse Architectures (open access)

Extreme Scaling of Production Visualization Software on Diverse Architectures

We present the results of a series of experiments studying how visualization software scales to massive data sets. Although several paradigms exist for processing large data, we focus on pure parallelism, the dominant approach for production software. These experiments utilized multiple visualization algorithms and were run on multiple architectures. Two types of experiments were performed. For the first, we examined performance at massive scale: 16,000 or more cores and one trillion or more cells. For the second, we studied weak scaling performance. These experiments were performed on the largest data set sizes published to date in visualization literature, and the findings on scaling characteristics and bottlenecks contribute to understanding of how pure parallelism will perform at high levels of concurrency and with very large data sets.
Date: December 22, 2009
Creator: Childs, Henry; Pugmire, David; Ahern, Sean; Whitlock, Brad; Howison, Mark; Weber, Gunther et al.
Object Type: Article
System: The UNT Digital Library
Investigating the possibility of a human component in various Pacific Decadal Oscillation indices (open access)

Investigating the possibility of a human component in various Pacific Decadal Oscillation indices

None
Date: December 22, 2009
Creator: Bonfils, C & Santer, B
Object Type: Article
System: The UNT Digital Library
Production and decay of element 114: high cross sections and the new nucleus 277Hs (open access)

Production and decay of element 114: high cross sections and the new nucleus 277Hs

The fusion-evaporation reaction {sup 244}Pu({sup 48}Ca,3-4n){sup 288,289}114 was studied at the new gas-filled recoil separator TASCA. Thirteen correlated decay chains were observed and assigned to the production and decay of {sup 288,289}114. At a compound nucleus excitation energy of E* = 39.8-43.9 MeV, the 4n evaporation channel cross section was 9.8{sub -3.1}{sup +3.9} pb. At E* = 36.1-39.5 MeV, that of the 3n evaporation channel was 8.0{sub -4.5}{sup +7.4} pb. In one of the 3n evaporation channel decay chains, a previously unobserved {alpha} branch in {sup 281}Ds was observed (probability to be of random origin from background: 0.1%). This {alpha} decay populated the new nucleus {sup 277}Hs, which decayed by spontaneous fission after a lifetime of 4.5 ms.
Date: December 22, 2009
Creator: Dullmann, Ch. E.; Schadel, M.; Yakushev, A.; Turler, A.; Eberhardt, K.; Kratz, J. V. et al.
Object Type: Article
System: The UNT Digital Library
Reaction of the C2H radical with 1-butyne (C4H6): Low Temperature Kinetics and Isomer-Specific Product Detection (open access)

Reaction of the C2H radical with 1-butyne (C4H6): Low Temperature Kinetics and Isomer-Specific Product Detection

The rate coefficient for the reaction of the ethynyl radical (C{sub 2}H) with 1-butyne (H-C{triple_bond}C-CH{sub 2}-CH{sub 3}) is measured in a pulsed Laval nozzle apparatus. Ethynyl radicals are formed by laser photolysis of acetylene (C{sub 2}H{sub 2}) at 193 nm and detected via chemiluminescence (C{sub 2}H + O{sub 2} {yields} CH (A{sup 2}{Delta}) + CO{sub 2}). The rate coefficients are measured over the temperature range of 74-295 K. The C{sub 2}H + 1-butyne reaction exhibits no barrier and occurs with rate constants close to the collision limit. The temperature dependent rate coefficients can be fit within experimental uncertainties by the expression k = (2.4 {+-} 0.5) x 10{sup -10} (T/295 K)-(0.04 {+-} 0.03) cm{sup 3} molecule{sup -1}s{sup -1}. Reaction products are detected at room temperature (295 K) and 533 Pa using a Multiplexed Photoionization Mass Spectrometer (MPIMS) coupled to the tunable VUV synchrotron radiation from the Advanced Light Source at the Lawrence Berkeley National Laboratory. Two product channels are identified for this reaction: m/z = 64 (C{sub 5}H{sub 4}) and m/z = 78 (C{sub 6}H{sub 6}) corresponding to the CH{sub 3}- and H-loss channels, respectively. Photoionization efficiency (PIE) curves are used to analyze the isomeric composition of both product channels. …
Date: December 22, 2009
Creator: Soorkia, Satchin; Trevitt, Adam J.; Selby, Talitha M.; Osborn, David L.; Taatjes, Craig A.; Wilson, Kevin R. et al.
Object Type: Article
System: The UNT Digital Library