The size effect of hematite and corundum inclusions on the efflorescence relative humidities of aqueous ammonium sulfate particles
Journal
Geophysical Research Letters
Journal Volume
28
Journal Issue
13
Pages
2601-2604
Date Issued
2001
Author(s)
Abstract
Mineral dusts inside aqueous atmospheric particles provide surfaces that induce crystallization during episodes of decreasing relative humidity (RH). Submicron aqueous ammonium sulfate particles containing hematite (α-Fe2O3) and corundum (α-Al2O3) inclusions are investigated in an aerosol flow tube at 298 K. As compared to 35% RH where homogeneous nucleation is rapid, the heterogeneous nuclei regulate the RH from 35% up to 60% RH as the inclusion size varies from 50 to 450 nm. The strong size dependence can be rationalized by an active site model. Model optimization yields 1010.4 sites cm−2 and in < 0 for α-Al2O3 and 109 sites cm−2 and in = 0.04 for α-Fe2O3 particles.
Type
journal article