Rapid Formation of Sulfuric Acid Particles at Near-Atmospheric Conditions

Abstract

We investigated the formation of new particles in a laboratory study, starting from H 2 SO 4 produced in situ through the reaction of OH radicals with SO 2 . Newly formed particles were observed for H 2 SO 4 concentrations above 7 × 10 6 per cubic centimeter. At 293 kelvin, a rough estimate yielded a nucleation rate of 0.3 to 0.4 particles per cubic centimeter per second for ∼10 7 particles per cubic centimeter of H 2 SO 4 (particle size ≥ 3 nanometers). These findings are in agreement with observations from the atmosphere. The results demonstrate that under laboratory conditions similar to the atmosphere, particle formation occurs at atmospheric H 2 SO 4 concentration levels.