Open AccessWater adsorption by hydrophobic organic surfaces: Experimental evidence and implications to the atmospheric properties of organic aerosols
Author(s) -
Thomas Elan,
Rudich Yi,
Trakhtenberg Sofia,
Ussyshkin Rachel
Publication year - 1999
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999jd900196
Subject(s) - adsorption , quartz crystal microbalance , relative humidity , monolayer , water vapor , materials science , chemical engineering , humidity , organic compound , quartz , langmuir , chemistry , nanotechnology , organic chemistry , thermodynamics , composite material , physics , engineering
The adsorption of water on hydrophobic organized organic thin films, used as a proxy for atmospheric organic aerosols, was measured simultaneously with a molecularly controlled semiconductor resistor (MOCSER) and quartz crystal microbalance (QCM). Water adsorption was found to be reversible and dependent on relative humidity (RH). The MOCSER measurements show that the adsorption kinetics of the first water layer resembles Langmuir behavior. The QCM findings indicate that adsorption is proportional to the water vapor pressure and exceeds the amount equivalent to one monolayer. These results can be explained by the formation of small water clusters on imperfections or structural defects on the organic surface and that the water does not achieve complete surface coverage even at high relative humidity. This mechanism resembles previous observations of water adsorption to structural defects on inorganic crystals. It is also shown that water can penetrate through the organic surface and reach the inorganic surface, even with a closely packed organic coating. This paper presents applications of these findings to the properties of organic aerosols.