Journal cover Journal topic
Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 3.400 IF 3.400
  • IF 5-year value: 3.841 IF 5-year
  • CiteScore value: 3.71 CiteScore
  • SNIP value: 1.472 SNIP 1.472
  • IPP value: 3.57 IPP 3.57
  • SJR value: 1.770 SJR 1.770
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 70 Scimago H
    index 70
  • h5-index value: 49 h5-index 49
Discussion papers
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 03 Feb 2020

Submitted as: research article | 03 Feb 2020

Review status
This preprint is currently under review for the journal AMT.

A Vacuum Ultraviolet Ion Source (VUV-IS) for Iodide-Chemical Ionization Mass Spectrometry: A Substitute for Radioactive Ion Sources

Yi Ji1, L. Gregory Huey1, David J. Tanner1, Young Ro Lee1, Patrick R. Veres2, J. Andrew Neuman2,3, Yuhang Wang1, and Xinming Wang4 Yi Ji et al.
  • 1School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
  • 2NOAA Earth System Research Laboratory (ESRL) Chemical Science Division, Boulder,Colorado, 80305, USA
  • 3Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, 80309, USA
  • 4State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China

Abstract. A new ion source (IS) utilizing vacuum ultraviolet (VUV) light is developed and characterized for use with iodide-chemical ionization mass spectrometers (I-CIMS). The VUV-IS utilizes a compact krypton lamp that emits light in two wavelength bands corresponding to energies of ~10.0 and 10.6 eV. The VUV light photoionizes either methyl iodide (ionization potential, IP = 9.54 ± 0.02 eV) or benzene (IP = 9.24378 ± 0.00007 eV) to form cations and photoelectrons. The electrons react with methyl iodide to form I which serves as the reagent ion for the CIMS. The VUV-IS is characterized by measuring the sensitivity of a quadrupole CIMS (Q-CIMS) to formic acid, molecular chlorine, and nitryl chloride under a variety of flow and pressure conditions. The sensitivity of the Q-CIMS, with the VUV-IS, reached up to ~700 Hz pptv−1, with detection limits of less than 1 pptv for a one minute integration period. The reliability of the Q-CIMS with a VUV-IS is demonstrated with data from a month long ground-based field campaign. The VUV-IS is further tested by operation on a high resolution time-of-flight CIMS (TOF-CIMS). Sensitivities greater than 25 Hz pptv−1 were obtained for formic acid and molecular chlorine, which were similar to that obtained with a radioactive source. In addition, the mass spectra from sampling ambient air was cleaner with the VUV-IS on the TOF-CIMS compared to measurements using a radioactive source. These results demonstrate that the VUV lamp is a viable substitute for radioactive ion sources on I-CIMS systems for most applications. In addition, the VUV-IS can likely be extended to other reagent ions, such as SF6 which are formed from high IP electron attachers, by the use of absorbers such as benzene to serve as a source of photoelectrons.

Yi Ji et al.

Interactive discussion

Status: open (until 30 Mar 2020)
Status: open (until 30 Mar 2020)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement

Yi Ji et al.


Total article views: 241 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
166 72 3 241 18 0 0
  • HTML: 166
  • PDF: 72
  • XML: 3
  • Total: 241
  • Supplement: 18
  • BibTeX: 0
  • EndNote: 0
Views and downloads (calculated since 03 Feb 2020)
Cumulative views and downloads (calculated since 03 Feb 2020)

Viewed (geographical distribution)

Total article views: 130 (including HTML, PDF, and XML) Thereof 129 with geography defined and 1 with unknown origin.
Country # Views %
  • 1



No saved metrics found.


No discussed metrics found.
Latest update: 17 Feb 2020
Publications Copernicus
Short summary
A common way of measuring trace gases in the atmosphere is chemical ionization mass spectrometry. One large drawback of these instrument is the need to use radioactive ion sources. In these work we demonstrate a simple ion source that uses a small lamp that is as effective as a radioactive source.
A common way of measuring trace gases in the atmosphere is chemical ionization mass...