A new instrument for thermal electron attachment at high temperature: NF3 and CH3Cl attachment rate constants up to 1100 K

Miller, Thomas M.; Friedman, Jeffrey F.; Williamson, John S.; Schaffer, Linda C.; Viggiano, A. A.

doi:10.1063/1.3097185

Cited by 21 publications

(19 citation statements)

References 58 publications

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“…They were typical of SIFT instruments of the day, being very large and heavy, following the precedence of the early flowing afterglow instruments (Ferguson, Fehsenfeld, & Schmeltekopf, 1969;Dunkin et al, 1968, Smith et al, 1975Adams & Smith, 1976), which surprisingly is still followed today when new laboratory research flow tube instruments are built (Van Doren et al, 2008;Miller et al, 2009). The flow tube was about a meter long and 8 cm diameter.…”

Section: A the Large Laboratory Sift-ms Instrumentmentioning

confidence: 97%

Progress in SIFT‐MS: Breath analysis and other applications

Španěl

Smith

2011

Mass Spectrometry Reviews

308

255

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The development of selected ion flow tube mass spectrometry, SIFT-MS, is described from its inception as the modified very large SIFT instruments used to demonstrate the feasibility of SIFT-MS as an analytical technique, towards the smaller but bulky transportable instruments and finally to the current smallest Profile 3 instruments that have been located in various places, including hospitals and schools to obtain on-line breath analyses. The essential physics and engineering principles are discussed, which must be appreciated to design and construct a SIFT-MS instrument. The versatility and sensitivity of the Profile 3 instrument is illustrated by typical mass spectra obtained using the three precursor ions H(3)O(+), NO(+) and O(2)(+)·, and the need to account for differential ionic diffusion and mass discrimination in the analytical algorithms is emphasized to obtain accurate trace gas analyses. The performance of the Profile 3 instrument is illustrated by the results of several pilot studies, including (i) on-line real time quantification of several breath metabolites for cohorts of healthy adults and children, which have provided representative concentration/population distributions, and the comparative analyses of breath exhaled via the mouth and nose that identify systemic and orally-generated compounds, (ii) the enhancement of breath metabolites by drug ingestion, (iii) the identification of HCN as a marker of Pseudomonas colonization of the airways and (iv) emission of volatile compounds from urine, especially ketone bodies, and from skin. Some very recent developments are discussed, including the quantification of carbon dioxide in breath and the combination of SIFT-MS with GC and ATD, and their significance. Finally, prospects for future SIFT-MS developments are alluded to.

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Section: A the Large Laboratory Sift-ms Instrumentmentioning

confidence: 97%

Progress in SIFT‐MS: Breath analysis and other applications

Španěl

Smith

2011

Mass Spectrometry Reviews

308

255

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“…The reader is referred to prior publications for further details on these instruments, with brief descriptions given here [19][20][21][22].…”

Section: Methodsmentioning

confidence: 99%

Electron attachment to the interhalogen compounds ClF, ICl, and IBr

et al. 2016

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Thermal electron attachment rate coefficients for three interhalogen compounds (ClF, ICl, IBr) have been measured from 300 to 900 K at pressures of 1-2 Torr using a flowing afterglow-Langmuir probe apparatus. ClF attaches somewhat inefficiently (k = 7.5×10 −9 cm 3 s −1 ) at 300 K, with the rate coefficient rising to 1.7×10 −8 cm 3 s −1 at 700 K. At higher temperatures the apparent rate coefficient falls steeply; however, this is interpreted as an artifact due to decomposition on the walls of the inlet line. ICl attaches with even lower efficiency (k = 9.5×10 −10 cm 3 s −1 at 300 K) and a less steep increase with temperature. Attachment to IBr is too slow to confidently measure with the present experiment, with an upper limit on the rate coefficient of 10 −10 cm 3 s −1 from 300 to 600 K. Both ClF and ICl attach dissociatively to yield Cl − , likely exclusively, though F − or I − may be produced with limits of <2% and <5%, respectively. The ClF attachment was further explored through ab initio calculation of the ClF and ClF − potential energy curves and R-matrix calculations of the resonance parameters which were used then for calculations of the dissociative attachment cross sections and rate coefficients. While the magnitude of the attachment rate coefficient for ClF is similar to those for both Cl 2 and F 2 , the calculated cross sections show qualitatively different threshold behavior due to the s-wave contribution allowed by the lack of inversion symmetry. The v = 1 and 2 vibrational modes of ClF attach about three to four times faster than v = 0 and 3 at energies lower than ∼0.2 eV. The calculated rate coefficients are in good agreement with the experiment at 300 K and increase moderately less steeply with temperature.

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“…[11][12][13] One apparatus was a conventional FALP apparatus normally used in the 300-550 K temperature range. 11,12 The second apparatus was a high-temperature FALP (HT-FALP, 300-1200 K).…”

Section: Experimental Technique and Resultsmentioning

confidence: 99%

Electron attachment to POCl3. III. Measurement and kinetic modeling of branching fractions

Shuman

Miller

Viggiano

et al. 2011

The Journal of Chemical Physics

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Analysis by kinetic modeling of the temperature dependence of thermal electron attachment to CF3Br J. Chem. Phys. 137, 024303 (2012) Electron attachment to POCl 3 was studied in the bath gas He over the pressure range 0.4-3.1 Torr and the temperature range 300-1210 K. Branching fractions of POCl 3 − , POCl 2 − , Cl − , and Cl 2 − were measured. The results are analyzed by kinetic modeling, using electron attachment theory for the characterization of the nonthermal energy distribution of the excited POCl 3 −* anions formed and chemical activation-type unimolecular rate theory for the subsequent competition between collisional stabilization of POCl 3 −* and its dissociation to various dissociation products. Primary and secondary dissociations and/or thermal dissociations of the anions are identified. The measured branching fractions are found to be consistent with the modeling results based on molecular parameters obtained from quantum-chemical calculations.

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A new instrument for thermal electron attachment at high temperature: NF3 and CH3Cl attachment rate constants up to 1100 K

Cited by 21 publications

References 58 publications

Progress in SIFT‐MS: Breath analysis and other applications

Progress in SIFT‐MS: Breath analysis and other applications

Electron attachment to the interhalogen compounds ClF, ICl, and IBr

Electron attachment to POCl3. III. Measurement and kinetic modeling of branching fractions

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