Influence of atmospheric conditions on the role of trifluoroacetic acid in atmospheric sulfuric acid–dimethylamine nucleation

Abstract

Abstract. Ambient measurements combined with theoretical simulations have shown evidence that the tropospheric degradation end-products of Freon alternatives, trifluoroacetic acid (TFA), one of the most important and abundant atmospheric organic substances, can enhance the nucleation process based on sulfuric acid (SA) and dimethylamine (DMA) in urban environments. However, TFA is widespread all over the world under different atmospheric conditions, such as temperature and nucleation precursor concentration, which are the most important factors potentially influencing the atmospheric nucleation process and thus inducing different nucleation mechanisms. Herein, using the density functional theory combined with the Atmospheric Cluster Dynamics Code, the influence of temperature and nucleation precursor concentrations on the role of TFA in the SA–DMA nucleation has been investigated. The results indicate that the growth trends of clusters involving TFA can increase with the decrease in temperature. The enhancement on particle formation rate by TFA and the contributions of the SA–DMA–TFA cluster to the cluster formation pathways can be up to 227-fold and 95 %, respectively, at relatively low temperature, low SA concentration, high TFA concentration, and high DMA concentration, such as in winter, at the relatively high atmospheric boundary layer, or in megacities far away from industrial sources of sulfur-containing pollutants. These results provide the perspective of the realistic role of TFA in different atmospheric environments, revealing the potential influence of the tropospheric degradation of Freon alternatives under a wide range of atmospheric conditions.

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2021

“…The dominant removal pathway for CF 3 CHO is photolysis (lifetime around one day) [ 50 ]. The formation of SOA can also be affected by TFA, which has recently been shown to enhance the formation of dimethylamine-sulphuric acid particles (up to two orders of magnitude under certain atmospheric conditions) [ 51 , 52 ]. This process can occur in winter with low sulphuric acid concentrations in the atmospheric boundary layer.…”

Enhancement of Atmospheric Nucleation Precursors on Iodic Acid-Induced Nucleation: Predictive Model and Mechanism

“…The Δ G values of dimer clusters provide critical information on the enhancing potential of atmospheric nucleation precursors on IA-induced nucleation. This study reveals the important contribution of XBs to the Δ G values, distinct from the SA/MSA-precursor systems. ,− ,,− This is the first evaluation of the enhancing potential of such a large number of precursors for IA-induced nucleation, expanding the current understanding of IA-induced nucleation. Furthermore, we developed a QSAR model to predict the Δ G values of other (IA) 1 (X) 1 dimer clusters based on the 63 calculated Δ G values.…”

Methanesulfonic acid and iodous acid nucleation: a novel mechanism for marine aerosols

“…When the cluster collision frequency exceeds its total evaporation frequency ( βC /Σ γ > 1), it can be considered to have potential to sustain growth. 53 Under the conditions of [HIO 2 ] = 2 × 10 6 molecules cm −3 (the measured concentration 22 ) and [MSA] = 1 × 10 6 molecules cm −3 (the median concentration 13 ), Fig. 5(a) and (b) present the values of βC /Σ γ for collision with HIO 2 and MSA, respectively.…”