Measurement of iodine species and sulfuric acid using bromide chemical ionization mass spectrometers
oleh: M. Wang, M. Wang, X.-C. He, H. Finkenzeller, S. Iyer, D. Chen, D. Chen, J. Shen, M. Simon, V. Hofbauer, V. Hofbauer, J. Kirkby, J. Kirkby, J. Curtius, N. Maier, T. Kurtén, T. Kurtén, D. R. Worsnop, D. R. Worsnop, M. Kulmala, M. Kulmala, M. Kulmala, M. Kulmala, M. Rissanen, M. Rissanen, R. Volkamer, Y. J. Tham, Y. J. Tham, N. M. Donahue, N. M. Donahue, N. M. Donahue, N. M. Donahue, M. Sipilä
| Format: | Article |
|---|---|
| Diterbitkan: | Copernicus Publications 2021-06-01 |
Deskripsi
<p>Iodine species are important in the marine atmosphere for oxidation and new-particle formation. Understanding iodine chemistry and iodine new-particle formation requires high time resolution, high sensitivity, and simultaneous measurements of many iodine species. Here, we describe the application of a bromide chemical ionization mass spectrometer (Br-CIMS) to this task. During the iodine oxidation experiments in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber, we have measured gas-phase iodine species and sulfuric acid using two Br-CIMS, one coupled to a Multi-scheme chemical IONization inlet (Br-MION-CIMS) and the other to a Filter Inlet for Gasses and AEROsols inlet (Br-FIGAERO-CIMS). From offline calibrations and intercomparisons with other instruments, we have quantified the sensitivities of the Br-MION-CIMS to HOI, I<span class="inline-formula"><sub>2</sub></span>, and H<span class="inline-formula"><sub>2</sub></span>SO<span class="inline-formula"><sub>4</sub></span> and obtained detection limits of 5.8 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>6</sup></span>, 3.8 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>5</sup></span>, and 2.0 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>5</sup></span> molec. cm<span class="inline-formula"><sup>−3</sup></span>, respectively, for a 2 min integration time. From binding energy calculations, we estimate the detection limit for HIO<span class="inline-formula"><sub>3</sub></span> to be 1.2 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>5</sup></span> molec. cm<span class="inline-formula"><sup>−3</sup></span>, based on an assumption of maximum sensitivity. Detection limits in the Br-FIGAERO-CIMS are around 1 order of magnitude higher than those in the Br-MION-CIMS; for example, the detection limits for HOI and HIO<span class="inline-formula"><sub>3</sub></span> are 3.3 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>7</sup></span> and 5.1 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>6</sup></span> molec. cm<span class="inline-formula"><sup>−3</sup></span>, respectively. Our comparisons of the performance of the MION inlet and the FIGAERO inlet show that bromide chemical ionization<span id="page4188"/> mass spectrometers using either atmospheric pressure or reduced pressure interfaces are well-matched to measuring iodine species and sulfuric acid in marine environments.</p>