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31 results on '"Klemm, R. Bruce"'

1. Heat of formation of OBrO: Experimental photoionization study

Author

Klemm, R. Bruce, Thorn, R. Peyton, Jr., Stief, Louis J., Buckley, Thomas J., and Johnson, Russell D.

Subjects
Bromides -- Chemical properties, Photoionization -- Methods, Chemicals, plastics and rubber industries
Abstract

The appearance of energy of BrO(super +) from the dissociative ionization of OBrO was determined from the photoionization efficiency spectrum of BrO(super +) over the wavelength range 90-122 nm by using a discharge flow-photoionization mass spectrometer apparatus coupled to a vacuum-ultraviolet synchrotron radiation source. The results are perturbed by a signal from BrO(Super +) formed by direct photoionization of BrO and by the dissociative ionization of Br2O.

Published
2001

2. Photoionization efficiency spectrum and ionization energy of OBrO

Author

Thorn, R. Peyton, Jr., Stief, Louis J., Buckley, Thomas J., Johnson, Russell D., III, Monks, Paul S., and Klemm, R. Bruce

Subjects
Chemistry, Physical and theoretical -- Research, Ionization -- Research, Bromine -- Research, Photoionization -- Research, Chemicals, plastics and rubber industries
Abstract

Measurements of the photoionization efficiency spectrum of OBrO have been performed by means of the flow-photoionization mass spectrometer. Results obtained with the previous determinations of the ionization energy for halogen monoxides and halogen dioxides are presented.

Published
1999

3. Photoionization mass spectrometric study of HOCl: photoionization efficiency spectrum and ionization energy

Author

Thorn, R. Peyton, Jr., Stief, Louis J., Kuo, Szu-Cherng, and Klemm, R. Bruce

Subjects
Organic acids -- Research, Mass spectrometry -- Usage, Chemicals, plastics and rubber industries
Abstract

A study was conducted to analyze the photoionization efficiency spectrum and ionization energy of hypochlorous acid (HOCl). A discharge flow-photoionization mass spectrometer coupled to a synchrotron radiation source was utilized to carry out the analysis. HOCL was produced within a glass sample bulb from a sequence of reactions. The experiments were carried at ambient temperature supporting a flow reactor pressure of about 4.3 +/- 0.1 Torr.

Published
1999

4. Photoionization-efficiency spectrum and ionization energy of the cyanomethyl radical CH2CN and products of the N(4S) + C2H3 reaction

Author

Thorn, R. Peyton, Jr., Monks, Paul S., Stief, Louis J., Kuo, Szu-Cherng, Zhang, Zhengyu, Ross, Stuart K., and Klemm, R. Bruce

Subjects
Photoionization -- Research, Methyl groups -- Research, Radicals (Chemistry) -- Research, Acetonitrile -- Research, Chemicals, plastics and rubber industries
Abstract

Research was conducted to examine the photoionization efficiency (PIE) spectra of the CH2CH radical over the wavelength range eta = 115-130 nm using a discharge-flow-photoionization mass spectrometer coupled to a dispersed synchrotron-radiation source. The experimental result for CH2CN is compared with previous measurements, estimates and calculations. The PIE spectra of the C2H2N radical and C2H3N adduct molecule formed in the reaction N(4S) + C2H3 was also investigated.

Published
1998

5. Heat of Formation of OBrO: An Experiment Photoionization Study

Author

Klemm, R. Bruce, Thorn, R. Peyton, Stief, Louis J, Buckley, Thomas J, and Vondrak, Richard R

Subjects
Geophysics
Abstract

The potential importance of OBrO in atmospheric chemistry has been suggested recently. Although there appear to be no experimental measurements of deltaH(OBrO), estimated values range from 70 to 152 kJ/mol. In the present investigation, the appearance energy (AE) of BrO+ from OBrO was measured by employing a discharge flow-photoionization mass spectrometer that is operated at beamline U-11. The heat of formation was derived from the AE result and the ionization energy of OBrO [IE = 10.29 eV]. The AE experiments yield a threshold at about 98.7 nm that gives, in turn, a value for AH(OBrO) of 180 +/- 10 kJ/mol. The difference with the estimated values mentioned above and the concomitant implications for the atmospheric reactions of OBrO will be discussed.

Published
2000

6. A discharge flow-photoionization mass spectrometric study of the FO(X 2 Pi i) radical. Photoionization efficiency spectrum and ionization energy

Author

Zhang, Zhengyu, Kuo, Szu-Cherng, Klemm, R. Bruce, Monks, Paul S, and Stief, Louis J

Subjects
Atomic And Molecular Physics
Abstract

Photoionization efficiency spectra of FO were measured over the wavelength range 80.0-100.0 nm and in the ionization threshold region, 94.0-100.0 nm, using a discharge flow-photoionization mass spectrometer apparatus coupled to a synchrotron radiation source. FO was generated by the reaction of F2P atoms with NO3 and via a F2O2 discharge. A value of 12.78 +/- 0.03 eV was obtained for the adiabatic ionization energy of FO from photoion thresholds which corresponds to FO(+)(X 3 Sigma -) from FO(X 2 Pi i). These results, which are the first to be obtained by direct Photo-ionization mass spectrometry (PIMS) measurements, corroborate those of a photoelectron spectroscopy (PES) study; however, the ionization energy determined here is free from interferences due to other species which complicated the PES measurement. A value of 109.5 +/- 8.0 kJ/mol for Delta f H 0 298(FO) is computed from the present value of IE(FO) and a previous appearance energy measurement, and a value for the proton affinity of FO is calculated to be 511.5 +/- 10.0 kJ/mol.

Published
1994
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7. Evaluation of the rate constant for the reaction OH+H2CO: Application of modeling and sensitivity analysis techniques for determination of the product branching ratio.

Author

Yetter, Richard A., Rabitz, Herschel, Dryer, Frederick L., Maki, Robert G., and Klemm, R. Bruce

Subjects
HYDROGEN, MOLECULAR dynamics, CHEMICAL reactions
Abstract

Novel modeling and sensitivity analysis techniques are used with experimental data obtained from discharge flow–resonance fluorescence experiments to evaluate the product branching ratio of OH+H2CO. Two channels are considered: the H-atom abstraction reaction (R2) to form HCO and H2O; and the addition reaction (R17) followed by rearrangement and decomposition to form HCOOH and H. The rate constant values obtained at 298 K are kR2 =(7.75±1.24)×10-12 cm3/molecule s and kR17=(0.2+0.8-0.2) ×10-12 cm3/molecule s. The results demonstrate that the reaction proceeds almost exclusively via the H-atom abstraction pathway. [ABSTRACT FROM AUTHOR]

Published
1989
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