Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry.

Linda Rondo ,J Hakala,J Kirkby,J Kim,P Vaattovaara,Federico Bianchi ,Paul M Winkler ,António Tomé ,Douglas R Worsnop ,Neil M Donahue ,Richard C Flagan ,Katrianne Lehtipalo ,Siegfried Schobesberger ,Alexey Adamov ,Tuukka Petäj̈ä ,Arnaud P Praplan ,Sebastian Ehrhart ,Nina Sarnela ,Armin Hansel ,Martin Breitenlechner ,Eimear M Dunne ,Urs Baltensperger ,Francesco Riccobono ,Matti Rissanen ,Christina Williamson ,James N Smith ,Markku Kulmala ,Andreas Kürten ,Markus Leiminger ,Mario Simon ,Alessandro Franchin ,Tuija Jokinen ,Jonathan Duplissy ,Daniela Wimmer ,Mikko Sipilä ,Helmi Keskinen ,Josef Dommen ,Georgios Tsagkogeorgas ,Jasmin Tröstl ,Joachim Curtius

doi:10.1002/2015jd023868

Abstract

Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI‐APi‐TOF (Chemical Ionization‐Atmospheric Pressure interface‐Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI‐APi‐TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4‐H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self‐contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

Highlights

Clouds play a key role in the Earth’s climate
In the present study the effect of dimethylamine on the derived sulfuric acid concentration is investigated from data obtained during nucleation experiments, where the sulfuric acid monomer and its clusters were measured under varying conditions
The capability of sulfuric acid molecules to bind with base molecules such as ammonia (NH3) and dimethylamine (DMA) leading to the formation of larger clusters and particles has been demonstrated in earlier studies [Kirkby et al, 2011; Almeida et al, 2013; Bianchi et al, 2014; Kürten et al, 2014]

Summary

Introduction

The climate forcing due to aerosol-climate interaction causes the largest source of uncertainty in present climate models [Intergovernmental Panel on Climate Change, 2001]. Much of the uncertainty regarding the effect of clouds on climate arises from the complexity of cloud formation. One important source for the atmospheric particle population, which links directly to the cloud formation via the global cloud condensation nuclei [Merikanto et al, 2010], is nucleation [Kulmala et al, 2013]. The exact mechanisms for particle nucleation and growth are still under investigation since knowledge of the cluster composition is required to fully understand new particle formation. One of the primary vapors responsible for nucleation is sulfuric acid (H2SO4) [Kulmala et al, 2004, 2006; Riipinen et al, 2007]. Since the observed atmospheric particle formation in the boundary layer

Methods

Results

Conclusion