TY - JOUR
T1 - Proton Transfer in Mixed Clusters of Methanesulfonic Acid, Methylamine, and Oxalic Acid
T2 - Implications for Atmospheric Particle Formation
AU - Xu, Jing
AU - Finlayson-Pitts, Barbara J.
AU - Gerber, R. Benny
N1 - Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/3/30
Y1 - 2017/3/30
N2 - Understanding the properties of atmospheric particles made of several components is a very challenging problem. In this paper, we perform quantum chemical calculations for small multicomponent clusters of atmospheric relevance that incorporate methanesulfonic acid (MSA), methylamine (MA), oxalic acid (OxA), and water (H2O). Potential correlations between theoretical predictions of proton transfer in the small clusters and findings of recent experiments on formation of particles of detectable sizes (>2 nm) from the same components are studied. It is proposed that proton transfer from the acid to the amine in the 1:1 clusters correlates with experiments on particle formation in systems, such as MSA-MA and MSA-MA-OxA. In the case of OxA + MA, which has been observed to give few particles, proton transfer does not occur for the 1:1 cluster but does for the 2:2 cluster. Adding H2O to OxA-MA promotes the occurrence of proton transfer, and corresponding particles are slightly enhanced. The partial charge on the MA component increases by adding OxA or H2O to MSA-MA, which is correlated with enhanced particle formation compared to MSA-MA alone. Ab initio molecular dynamics simulations show that proton transfer at room temperature (T = 298 K) and high temperature (T = 500 K) is little affected compared with the equilibrium structure (T = 0 K). These results suggest that small cluster calculations may be useful in predicting the formation of multicomponent particles in the atmosphere.
AB - Understanding the properties of atmospheric particles made of several components is a very challenging problem. In this paper, we perform quantum chemical calculations for small multicomponent clusters of atmospheric relevance that incorporate methanesulfonic acid (MSA), methylamine (MA), oxalic acid (OxA), and water (H2O). Potential correlations between theoretical predictions of proton transfer in the small clusters and findings of recent experiments on formation of particles of detectable sizes (>2 nm) from the same components are studied. It is proposed that proton transfer from the acid to the amine in the 1:1 clusters correlates with experiments on particle formation in systems, such as MSA-MA and MSA-MA-OxA. In the case of OxA + MA, which has been observed to give few particles, proton transfer does not occur for the 1:1 cluster but does for the 2:2 cluster. Adding H2O to OxA-MA promotes the occurrence of proton transfer, and corresponding particles are slightly enhanced. The partial charge on the MA component increases by adding OxA or H2O to MSA-MA, which is correlated with enhanced particle formation compared to MSA-MA alone. Ab initio molecular dynamics simulations show that proton transfer at room temperature (T = 298 K) and high temperature (T = 500 K) is little affected compared with the equilibrium structure (T = 0 K). These results suggest that small cluster calculations may be useful in predicting the formation of multicomponent particles in the atmosphere.
UR - http://www.scopus.com/inward/record.url?scp=85019841981&partnerID=8YFLogxK
U2 - 10.1021/acs.jpca.7b01223
DO - 10.1021/acs.jpca.7b01223
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C2 - 28287734
AN - SCOPUS:85019841981
SN - 1089-5639
VL - 121
SP - 2377
EP - 2385
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 12
ER -