Activation of sub 2 nm Water Soluble and Insoluble Standard Ions with Saturated Vapors of Butanol in a Boosted TSI Ultrafine CPC.

Tetraheptylammonium bromide (THABr), tetrabutylammonium bromide (TBABr) and tetraethylammonium bromide (TEABr) dissolved in methanol or water methanol mixtures (~ 1mM) produce via positive electrospray atomization and high resolution classification electrical classification standard clean ions (monomer and dimer) which are singly charged. THABr is hydrophobic and insoluble in water, TBABr and TEABr are hygroscopic and water soluble (0.6 and 2.8 kg/l respectively). These ions are used to study the effect of hygroscopicity on the activation of aerosol particles in the sub 2 nm range via the detection efficiency measurement of a boosted ultrafine TSI condensation particle counter (3025A). Water solubility of particles seems to play a role in the activation and growth with butanol vapor in the CPC (condensation particle counter) independently of the size