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, I₂, and H₂SO₄ and obtained detection limits of 5.8 × 10⁶, 3.8 × 10⁵, and 2.0 × 10⁵ molec. cm⁻³, respectively, for a 2 min integration time. From binding energy calculations, we estimate the detection limit for HIO₃ to be 1.2 × 10⁵ molec. cm⁻³, 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 HIO₃ are 3.3 × 10⁷ and 5.1 × 10⁶ molec. cm⁻³, respectively. Our comparisons of the performance of the MION inlet and the FIGAERO inlet show that bromide chemical ionization mass spectrometers using either atmospheric pressure or reduced pressure interfaces are well-matched to measuring iodine species and sulfuric acid in marine environments.

中文翻译：

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使用溴化物化学电离质谱仪测量碘种类和硫酸

碘物质在海洋大气中对于氧化和新粒子形成很重要。了解碘化学和碘新粒子的形成需要高时间分辨率、高灵敏度和多种碘物质的同时测量。在这里，我们描述了溴化物化学电离质谱仪 (Br-CIMS) 在此任务中的应用。在 Cosmics Leaving OUTdoor Droplets (CLOUD) 室中的碘氧化实验中，我们使用两个 Br-CIMS 测量了气相碘物质和硫酸，其中一个与多方案化学电离入口 (Br-MION-CIMS) 耦合另一个连接到气体过滤器入口和气溶胶入口 (Br-FIGAERO-CIMS)。通过离线校准和与其他仪器的比对，我们量化了 Br-MION-CIMS 对 HOI 的敏感性，I₂、H ₂ SO ₄，得到5.8  ×  10 ⁶、3.8  ×  10 ⁵、2.0  ×  10 ⁵  molc的检出限。cm ^-3，分别为 2 分钟的积分时间。根据结合能计算，我们估计 HIO ₃的检测限为1.2  ×  10 ⁵ 摩尔。cm ^-3，基于最大灵敏度的假设。Br-FIGAERO-CIMS 的检测限比 Br-MION-CIMS 的检测限高约 1 个数量级；例如，HOI 和 HIO ₃的检测限为3.3 ×  10 ⁷和 5.1  ×  10 ⁶ 摩尔。cm ^-3，分别。我们对 MION 进样口和 FIGAERO 进样口性能的比较表明，溴化物化学电离 使用大气压或减压接口的质谱仪非常适合测量海洋环境中的碘种类和硫酸。