Laboratory observations of temperature and humidity dependencies of nucleation and growth rates of sub‐3 nm particles

Abstract

Temperature and relative humidity (RH) are the most important thermodynamic parameters in aerosol formation, yet laboratory studies of nucleation and growth dependencies on temperature and RH are lacking. Here we report the experimentally observed temperature and RH dependences of sulfuric acid aerosol nucleation and growth. Experiments were performed in a flow tube in the temperature range from 248 to 313 K, RH from 0.8% to 79%, and relative acidity (RA) of sulfuric acid from 6 × 10−5 to 0.38 (2 × 107–109 cm−3). The impurity levels of base compounds were determined to be NH3 < 23 pptv (parts per thousand by volume), methylamine < 1.5 pptv, and dimethylamine < 0.52 pptv. Our results showed that low temperatures favor nucleation at fixed sulfuric acid concentration but impede nucleation when RA is fixed. It is also shown that binary nucleation of sulfuric acid and water is negligible in planetary boundary layer temperature and sulfuric acid ranges. An empirical algorithm was derived to correlate the nucleation rate with RA, RH, and temperature together. Collision‐limited condensation of free‐sulfuric acid molecules fails to predict the observed growth rate in the sub‐3 nm size range, as well as its dependence on temperature and RH. This suggests that evaporation, sulfuric acid hydration, and possible involvement of other ternary molecules should be considered for the sub‐3 nm particle growth.

New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

“…Experiments often suffer various contaminations of nucleation precursors, especially relatively high concentrations of amines and ammonia that originate from deionized water. For example, flow tubes (e.g., made by Pyrex) typically contain the pptv and tens pptv level of base compounds depending on RH, even after very deliberate cleaning processes (Erupe et al, ; Yu, Dai, et al, ; Yu, McGraw, & Lee, ), with some exceptions (Glasoe et al, ; Hanson et al, ). As nucleation is a nonlinear process and the J are extremely sensitive to the temperature, RH, and concentrations of nucleation precursors, it is difficult to obtain consistent data from different experimental setups.…”

“…Yu, Dai, et al () performed flow tube experiments of sulfuric acid aerosol nucleation, at temperatures ranging from 248 to 313 K, RH from 1% to 79%, and under minimal base concentrations (ammonia < 23 pptv, methylamine < 1.5 pptv, and DMA < 0.52 pptv). Yu, Dai, et al () provided for the first time the temperature and RH dependence of both J and GR . J shows the following dependence within the experimental conditions: where RA is the saturation ratio (or relatively acidity) of sulfuric acid.…”

“…Kürten, Bianchi et al (2016) showed that ternary nucleation involving ammonia could be an important mechanism for nucleation in the polluted boundary layer when temperatures are not too high (e.g., 278 K). Yu, Dai, et al (2017) performed flow tube experiments of sulfuric acid aerosol nucleation, at temperatures ranging from 248 to 313 K, RH from 1% to 79%, and under minimal base concentrations (ammonia < 23 pptv, methylamine < 1.5 pptv, and DMA < 0.52 pptv). Yu, Dai, et al (2017) provided for the first time the temperature and RH dependence of both J and GR.…”

New particle formation in the sulfuric acid–dimethylamine–water system: reevaluation of CLOUD chamber measurements and comparison to an aerosol nucleation and growth model

“…The fact that the measured particle size distribution can be reproduced with good accuracy shows that neither water nor other species contribute significantly to particle growth during these CLOUD chamber experiments. Water could play a role at higher relative humidities, although quantum chemical calculations suggest that it plays only a minor role in NPF for the system of sulfuric acid and DMA (Olenius et al, 2017); this contrasts with the sulfuric acid-water system (see e.g., Zollner et al, 2012; al., 2016;Yu et al, 2017). In addition, it is not exactly known how temperature influences the cluster evaporation rates (Hanson et al, 2017).…”

Experimental study of H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; aerosol nucleation at high ionization levels

“…Few measurements exist that quantify parameters affecting and assisting nucleation (Berndt et al, 2006;Benson et al, 20 2011;Sipila et al, 2010;Kirkby et al, 2011;Svensmark et al, 2007;Enghoff et al, 2011;Yu et al, 2017). Recent laboratory measurements by Dunne et al (2016) determined the dependence on temperature, trace gas and ion concentrations and provided a parametrization that can be incorporated into climate models.…”