Measurement of ammonia, amines and iodine compounds using protonated water cluster chemical ionization mass spectrometry

Abstract

Abstract. Here we describe the design and performance of a new water cluster chemical ionization–atmospheric pressure interface time-of-flight mass spectrometer (CI-APi-TOF). The instrument selectively measures trace gases with high proton affinity such as ammonia and dimethylamine, which are important for atmospheric new particle formation and growth. Following the instrument description and characterization, we demonstrate successful measurements at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber where very low ammonia background levels of ∼4 pptv were achieved (at 278 K and 80 % RH). The limit of detection of the water cluster CI-APi-TOF is estimated to be ∼0.5 pptv for ammonia. Although no direct calibration was performed for dimethylamine (DMA), we estimate its detection limit is at least 3 times lower. Due to the short ion–molecule reaction time and high reagent ion concentrations, ammonia mixing ratios up to at least 10 ppbv can be measured with the instrument without significant reagent ion depletion. Besides the possibility to measure compounds like ammonia and amines (dimethylamine), we demonstrate that the ionization scheme is also suitable for the measurement of trace gases containing iodine. During CLOUD experiments to investigate the formation of new particles from I2, many different iodine-containing species were identified with the water cluster CI-APi-TOF. The compounds included iodic acid and neutral molecular clusters containing up to four iodine atoms. However, the molecular structures of the iodine-containing clusters are ambiguous due to the presence of an unknown number of water molecules. The quantification of iodic acid (HIO3) mixing ratios is performed from an intercomparison with a nitrate CI-APi-TOF. Using this method the detection limit for HIO3 can be estimated as 0.007 pptv. In addition to presenting our measurements obtained at the CLOUD chamber, we discuss the applicability of the water cluster Ci-APi-TOF for atmospheric measurements.

Enhanced growth rate of atmospheric particles from sulfuric acid

“…4b. In addition, we show the growth rates using the time-and sizeresolving growth rate analysis method INSIDE (Pichelstorfer et al, 2018), which agrees with the appearance time method, demonstrating a minor systematic bias in our growth rate determination. All approaches reproduce the size dependence at an acceptable level (R 2 larger than 0.87).…”

“…S1b). In the second method, we applied the size-and time-resolving growth rate analysis method "IN-SIDE" (INterpreting the change rate of the Size-Integrated general Dynamic Equation; Pichelstorfer et al, 2018) to cross-check our results. The INSIDE method uses the measured particle size distribution at a time t 1 and simulates the expected aerosol dynamics (coagulation, wall losses and dilution) until time t 2 .…”

Measurement of iodine species and sulfuric acid using bromide chemical ionization mass spectrometers

“…Reactive iodine species are released into the atmosphere mainly by biological processes in marine environments (i.e., from macro-and micro-algae) (McFiggans et al, 2004), O 3 deposition on the sea surface (Carpenter et al, 2013), and from the sea ice (Spolaor et al, 2013) and snowpack in the polar region (Raso et al, 2017). Once emitted, iodine species can modify atmospheric oxidative capacity via a chain of catalytic reactions with O 3 that form iodine oxides, leading to about 20 %-28 % of O 3 loss in the marine boundary layer (Prados-Roman et al, 2015;Sherwen et al, 2016). Through convection, reactive iodine species can be transported from the lower troposphere to the upper troposphere-lower stratosphere, causing one third of the iodine-induced ozone loss in the upper troposphere-lower stratosphere (Koenig et al, 2020).…”

The driving factors of new particle formation and growth in the polluted boundary layer

“…Extremely high NPF rates are frequently observed in the polluted boundary layer, although current understanding suggests that newly formed particles should be rapidly scavenged by the high concentration of preexisting aerosols (Kulmala et al, 2017). Different vapours have been postulated to participate in NPF, including sulfuric acid, ammonia (Kirkby et al, 2011;, amines (Almeida et al, 2013) and organics (Kirkby et al, 2016;Lehtipalo et al, 2018;Riccobono et al, 2014).…”