Sensitive Mass Spectrometer for Time-Resolved Gas-Phase Chemistry Studies at High Pressures
Abstract
Here, we report the construction of a new experimental apparatus for direct time-resolved probing of high-pressure gas-phase chemical reactions by photoionization mass spectrometry. The apparatus uses a laser photolysis slow-flow reactor, capable of operating at P = 0.3 — 100 bar and T = 300 — 1000 K. In this report, we initiate reactions in homogeneous gas mixtures by the photolysis of appropriate radical precursor using laser pulses at repetition rates of 1 — 10 Hz. The reacting mixture is continuously sampled into a vacuum chamber, ionized by VUV photons from laboratory-based discharge lamps or from a synchrotron beamline, and analyzed by a custom-designed mass spectrometer. Soft near-threshold ionization by tunable synchrotron radiation enables spectroscopic quantification of many key intermediates and products of chemical reactions. A novel ionization scheme in the high-density region of the sample gas jet increases the experimental sensitivity 100-fold, compared with existing instruments, without compromising mass resolution. A 40-kHz pulsed reflectron time-of-flight mass spectrometer in the orthogonal acceleration geometry achieves simultaneous detection of all ionized species with 25-μs time resolution. We show the power of this apparatus by investigating the ethyl radical oxidation reaction using very dilute (<1012 molecules • cm-3) ethyl concentrations at pressures upmore »
- Authors:
-
- Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- Publication Date:
- Research Org.:
- Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
- OSTI Identifier:
- 1574695
- Report Number(s):
- SAND-2019-10135J
Journal ID: ISSN 1089-5639; 678901; TRN: US2001320
- Grant/Contract Number:
- AC04-94AL85000; NA0003525; AC02-05CH11231
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
- Additional Journal Information:
- Journal Volume: 123; Journal Issue: 50; Journal ID: ISSN 1089-5639
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 47 OTHER INSTRUMENTATION
Citation Formats
Sheps, Leonid, Antonov, Ivan, and Au, Kendrew. Sensitive Mass Spectrometer for Time-Resolved Gas-Phase Chemistry Studies at High Pressures. United States: N. p., 2019.
Web. doi:10.1021/acs.jpca.9b08393.
Sheps, Leonid, Antonov, Ivan, & Au, Kendrew. Sensitive Mass Spectrometer for Time-Resolved Gas-Phase Chemistry Studies at High Pressures. United States. doi:10.1021/acs.jpca.9b08393.
Sheps, Leonid, Antonov, Ivan, and Au, Kendrew. Mon .
"Sensitive Mass Spectrometer for Time-Resolved Gas-Phase Chemistry Studies at High Pressures". United States. doi:10.1021/acs.jpca.9b08393. https://www.osti.gov/servlets/purl/1574695.
@article{osti_1574695,
title = {Sensitive Mass Spectrometer for Time-Resolved Gas-Phase Chemistry Studies at High Pressures},
author = {Sheps, Leonid and Antonov, Ivan and Au, Kendrew},
abstractNote = {Here, we report the construction of a new experimental apparatus for direct time-resolved probing of high-pressure gas-phase chemical reactions by photoionization mass spectrometry. The apparatus uses a laser photolysis slow-flow reactor, capable of operating at P = 0.3 — 100 bar and T = 300 — 1000 K. In this report, we initiate reactions in homogeneous gas mixtures by the photolysis of appropriate radical precursor using laser pulses at repetition rates of 1 — 10 Hz. The reacting mixture is continuously sampled into a vacuum chamber, ionized by VUV photons from laboratory-based discharge lamps or from a synchrotron beamline, and analyzed by a custom-designed mass spectrometer. Soft near-threshold ionization by tunable synchrotron radiation enables spectroscopic quantification of many key intermediates and products of chemical reactions. A novel ionization scheme in the high-density region of the sample gas jet increases the experimental sensitivity 100-fold, compared with existing instruments, without compromising mass resolution. A 40-kHz pulsed reflectron time-of-flight mass spectrometer in the orthogonal acceleration geometry achieves simultaneous detection of all ionized species with 25-μs time resolution. We show the power of this apparatus by investigating the ethyl radical oxidation reaction using very dilute (<1012 molecules • cm-3) ethyl concentrations at pressures up to 25 bar.},
doi = {10.1021/acs.jpca.9b08393},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
number = 50,
volume = 123,
place = {United States},
year = {2019},
month = {11}
}
Web of Science