Prompt deliquescence and efflorescence of aerosol nanoparticles G. Biskos1, D. Paulsen1, L. M. Russell2, P. R. Buseck3, and S. T. Martin1 1Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA 2Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA 3Departments of Geological Sciences and Chemistry/Biochemistry, Arizona State University, Tempe, AZ 85287, USA
Abstract. Literature reports have differed on the possibilities of discontinuous and
continuous (i.e., prompt and nonprompt) deliquescence and efflorescence of
aerosol particles in the nanosize regime. Experiments reported herein using
a hygroscopic tandem nano-differential mobility analyzer demonstrate prompt
deliquescence and efflorescence of ammonium sulfate particles having
diameters from 6 to 60 nm. Apparent nonpromptness can be induced both by
operation of the experimental apparatus and by interpretation of the
measurements, even though the underlying phase transitions of individual
particles remain prompt. No nanosize effect on the relative humidity values
of deliquescence or efflorescence is observed for the studied size range.
Smaller hygroscopic growth factors are, however, observed for the
nanoparticles, in agreement with thermodynamic calculations that include the
Kelvin effect. A slightly nonspherical shape for dry ammonium sulfate
particles is inferred from their hygroscopically induced reconstruction
between 5 and 30% relative humidity. Our results provide a further
understanding of nanoparticle behavior, especially relevant to the growth
rates of atmospheric nanoparticles.
Citation: Biskos, G., Paulsen, D., Russell, L. M., Buseck, P. R., and Martin, S. T.: Prompt deliquescence and efflorescence of aerosol nanoparticles, Atmos. Chem. Phys., 6, 4633-4642, doi:10.5194/acp-6-4633-2006, 2006.