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Title: Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies

Abstract

A shock tube (ST) with online, time-of-flight mass spectrometric (TOF-MS) detection has been constructed for the study of elementary reactions at high temperature. The ST and TOF-MS are coupled by a differentially pumped molecular beam sampling interface, which ensures that the samples entering the TOF-MS are not contaminated by gases drawn from the cold end wall thermal boundary layer in the ST. Additionally, the interface allows a large range of postshock pressures to be used in the shock tube while maintaining high vacuum in the TOF-MS. The apparatus and the details of the sampling system are described along with an analysis in which cooling of the sampled gases and minimization of thermal boundary layer effects are discussed. The accuracy of kinetic measurements made with the apparatus has been tested by investigating the thermal unimolecular dissociation of cyclohexene to ethylene and 1,3-butadiene, a well characterized reaction for which considerable literature data that are in good agreement exist. The experiments were performed at nominal reflected shock wave pressures of 600 and 1300 Torr, and temperatures ranging from 1260 to 1430 K. The rate coefficients obtained are compared with the earlier shock tube studies and are found to be in very good agreement.more » As expected no significant difference is observed in the rate constant between pressures of 600 and 1300 Torr.« less

Authors:
; ;  [1];  [2]
  1. Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439-4831 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20953393
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 78; Journal Issue: 3; Other Information: DOI: 10.1063/1.2437150; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ACCURACY; BOUNDARY LAYERS; BUTADIENE; CHEMICAL ANALYSIS; EQUIPMENT; ETHYLENE; GASES; MASS SPECTROSCOPY; MOLECULAR BEAMS; REACTION KINETICS; SAMPLING; SHOCK TUBES; SHOCK WAVES; TEMPERATURE RANGE 0400-1000 K; TIME-OF-FLIGHT MASS SPECTROMETERS; TIME-OF-FLIGHT METHOD

Citation Formats

Tranter, Robert S., Giri, Binod R., Kiefer, John H., and Department of Chemical Engineering, University of Illinois at Chicago, 810 S. Clinton Street, Chicago, Illinois 60607. Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies. United States: N. p., 2007. Web. doi:10.1063/1.2437150.
Tranter, Robert S., Giri, Binod R., Kiefer, John H., & Department of Chemical Engineering, University of Illinois at Chicago, 810 S. Clinton Street, Chicago, Illinois 60607. Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies. United States. doi:10.1063/1.2437150.
Tranter, Robert S., Giri, Binod R., Kiefer, John H., and Department of Chemical Engineering, University of Illinois at Chicago, 810 S. Clinton Street, Chicago, Illinois 60607. Thu . "Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies". United States. doi:10.1063/1.2437150.
@article{osti_20953393,
title = {Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies},
author = {Tranter, Robert S. and Giri, Binod R. and Kiefer, John H. and Department of Chemical Engineering, University of Illinois at Chicago, 810 S. Clinton Street, Chicago, Illinois 60607},
abstractNote = {A shock tube (ST) with online, time-of-flight mass spectrometric (TOF-MS) detection has been constructed for the study of elementary reactions at high temperature. The ST and TOF-MS are coupled by a differentially pumped molecular beam sampling interface, which ensures that the samples entering the TOF-MS are not contaminated by gases drawn from the cold end wall thermal boundary layer in the ST. Additionally, the interface allows a large range of postshock pressures to be used in the shock tube while maintaining high vacuum in the TOF-MS. The apparatus and the details of the sampling system are described along with an analysis in which cooling of the sampled gases and minimization of thermal boundary layer effects are discussed. The accuracy of kinetic measurements made with the apparatus has been tested by investigating the thermal unimolecular dissociation of cyclohexene to ethylene and 1,3-butadiene, a well characterized reaction for which considerable literature data that are in good agreement exist. The experiments were performed at nominal reflected shock wave pressures of 600 and 1300 Torr, and temperatures ranging from 1260 to 1430 K. The rate coefficients obtained are compared with the earlier shock tube studies and are found to be in very good agreement. As expected no significant difference is observed in the rate constant between pressures of 600 and 1300 Torr.},
doi = {10.1063/1.2437150},
journal = {Review of Scientific Instruments},
number = 3,
volume = 78,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • No abstract prepared.
  • A conventional membrane-type stainless steel shock tube has been coupled to a high-repetition-rate time-of-flight mass spectrometer (HRR-TOF-MS) to be used to study complex reaction systems such as the formation of pollutants in combustion processes or formation of nanoparticles from metal containing organic compounds. Opposed to other TOF-MS shock tubes, our instrument is equipped with a modular sampling unit that allows to sample with or without a skimmer. The skimmer unit can be mounted or removed in less than 10 min. Thus, it is possible to adjust the sampling procedure, namely, the mass flux into the ionization chamber of the HRR-TOF-MS,more » to the experimental situation imposed by species-specific ionization cross sections and vapor pressures. The whole sampling section was optimized with respect to a minimal distance between the nozzle tip inside the shock tube and the ion source inside the TOF-MS. The design of the apparatus is presented and the influence of the skimmer on the measured spectra is demonstrated by comparing data from both operation modes for conditions typical for chemical kinetics experiments. The well-studied thermal decomposition of acetylene has been used as a test system to validate the new setup against kinetics mechanisms reported in literature.« less
  • A new generation SVSCf-plasma desorption time-of-flight mass spectrometer has been developed and placed into operation. The new features address particular requirements for high-mass studies but the overall design has been to markedly increase the flexibility for carrying out a variety of different kinds of experiments. The new features include a provision for controlling the SVSCf source-target and target-acceleration grid distance, an IR diode array for identification and precise positioning of targets, and different configurations of the field-free and ion detector region for post-acceleration, metastable ion analysis, and velocity focusing. Improvements have also been made in the data acquisition and analysismore » programs specifically for high-mass studies in order to obtain more accurate masses and a more complete picture of the complete ion distribution by generating digital difference mass spectra.« less
  • A novel, diaphragmless shock tube (DFST) has been developed for use in high temperature chemical kinetic studies. The design of the apparatus is presented along with performance data that demonstrate the range and reproducibility of reaction conditions that can be generated. The ability to obtain data in the fall off region, confined to much narrower pressure ranges than can be obtained with a conventional shock tube is shown, and results from laser schlieren densitometry experiments on the unimolecular dissociation of phenyl iodide (P{sub 2} = 57{+-}9 and 122{+-}7 torr, T{sub 2} = 1250-1804K) are presented. These are compared with resultsmore » similar to those that would be obtained from a classical shock tube and the implications for extrapolation by theoretical methods are discussed. Finally, the use of the DFST with an online mass spectrometer to create reproducible experiments that can be signal averaged to improve signal/noise and the quality of mass peaks is demonstrated; something that is not possible with a conventional shock tube where each experiment has to be considered unique« less
  • A novel, diaphragmless shock tube (DFST) has been developed for use in high temperature chemical kinetic studies. The design of the apparatus is presented along with performance data that demonstrate the range and reproducibility of reaction conditions that can be generated. The ability to obtain data in the fall off region, confined to much narrower pressure ranges than can be obtained with a conventional shock tube is shown, and results from laser schlieren densitometry experiments on the unimolecular dissociation of phenyl iodide (P{sub 2}=57{+-}9 and 122{+-}7 torr, T{sub 2}=1250-1804 K) are presented. These are compared with results similar to thosemore » that would be obtained from a classical shock tube and the implications for extrapolation by theoretical methods are discussed. Finally, the use of the DFST with an online mass spectrometer to create reproducible experiments that can be signal averaged to improve signal/noise and the quality of mass peaks is demonstrated; something that is not possible with a conventional shock tube where each experiment has to be considered unique.« less