Vapor specific extents of uptake by nanometer scale charged particles

Abstract

ABSTRACTThe uptake of vapor molecules by nanometer scale aerosol particles (clusters) is of fundamental importance in aerosol science; uptake is the first step of condensational growth in both the ambient as well as in condensation based particle detectors. However, uptake is not well understood at the nanometer scale. We examined the uptake of organic vapor molecules by nanometer scale sodium chloride cluster ions ((NaCl)x(Na+)z and (NaCl)x(Cl−)z) using a differential mobility analyzer coupled with a time-of-flight mass spectrometer. Through monitoring cluster ion inverse mobilities as functions of solvent vapor pressure in the mobility analyzer, the extent of uptake was monitored for 1-butanol, ethanol, methyl ethyl ketone (MEK), and toluene. With butanol vapor pressures in the <300 Pa range, shifts in inverse mobility in excess of a factor of 2 were observed for nearly all examined clusters. Ethanol and MEK uptake led to shifts for positively charged cluster ions upwards of a factor of 1.5. Ethanol exp...