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

Abstract

No abstract prepared.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
940697
Report Number(s):
ANL/CHM/JA-57759
Journal ID: ISSN 0034-6748; RSINAK; TRN: US200824%%175
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Rev. Sci. Instrum.; Journal Volume: 78; Journal Issue: 3 ; 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 47 OTHER INSTRUMENTATION; KINETICS; TIME-OF-FLIGHT MASS SPECTROMETERS; DESIGN; PERFORMANCE

Citation Formats

Giri, B. R., Kiefer, J. H., Tranter, R. S., Chemistry, and Univ. of Illinois at Chicago. Shock tube/time-of-flight mass spectrometer for high temperature kinetics studies.. United States: N. p., 2007. Web.
Giri, B. R., Kiefer, J. H., Tranter, R. S., Chemistry, & Univ. of Illinois at Chicago. Shock tube/time-of-flight mass spectrometer for high temperature kinetics studies.. United States.
Giri, B. R., Kiefer, J. H., Tranter, R. S., Chemistry, and Univ. of Illinois at Chicago. Mon . "Shock tube/time-of-flight mass spectrometer for high temperature kinetics studies.". United States. doi:.
@article{osti_940697,
title = {Shock tube/time-of-flight mass spectrometer for high temperature kinetics studies.},
author = {Giri, B. R. and Kiefer, J. H. and Tranter, R. S. and Chemistry and Univ. of Illinois at Chicago},
abstractNote = {No abstract prepared.},
doi = {},
journal = {Rev. Sci. Instrum.},
number = 3 ; 2007,
volume = 78,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • 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 anmore » 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.« less
  • 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
  • The dissociation of 1,1,1,-trifluoroethane, a potential non-RRKM reaction, has been studied at 600 and 1200 Torr and high temperatures (1500-1840 K) using a new shock tube/time-of-flight mass spectrometer (ST/TOF-MS). These data obtained by an independent method are in good agreement with the laser schlieren, LS, experiments of Kiefer et al. [J. Phys. Chem. A 2004, 108, 2443-2450] and extend the range of that experimental dataset. The data have been simulated by both standard RRKM calculations and the non-RRKM model reported by Kiefer et al. but with <{Delta}E{sub down}> = 750 cm{sup -1}. Both the RRKM and non-RRKM calculations provide equallymore » good fits to the ST/TOF-MS data. Neither model simulates the combined ST/TOF-MS and LS datasets particularly well. However, the non-RRKM model predicts a pressure dependency closer to that observed in the experiments than the RRKM model.« less
  • The shifts in ion flight times produced by a flat-top potential barrier applied within the drift tube of a time-offlight mass spectrometer are defined analytically in terms of the height of the potential barrier. These flight-time shifts are selectively dependent on the mass, charge, and kinetic energy of the ions involved; consequently, they can be used to separate and identify the products of ion dissociation processes occurring in the drift tube. Comparisons of calculated and observed flight-time shifts for the 58/sup +/ yields 43/sup +/ , 42/sup +/ dissociations in n-butane are used to illustrate the applicability and present limitationsmore » of this method of identifying dissociation products. (auth)« less