Evidence for sub-3 nanometer neutralized particle detection using glycerol as a condensing fluid

A two-step condensation process was utilized, with glycerol introduced via an initial precondenser step, with secondary condensation and detection occurring within a traditional n-butanol operated condensation nucleus counter. Experimental results suggested that the size-threshold for detection by condensation nucleation was decreased by using glycerol versus n-butanol. Based on the predictions from particle size distributions, the smallest particles that could be detected were estimated to have diameters somewhere in the 0.55–1.7 nm range. Potential interferences due to incomplete droplet desolvation or penetration loss differences were predicted to have negligible impact on this estimation. A direct comparison of the capability of the precondenser system and the TSI UCPC 3025A to detect small particles was made, showing that the precondenser system could detect smaller particles (estimated as having diameters as small as 1.6–1.7 nm) than the UCPC 3025A when both systems were compared close to conditions of critical supersaturation in the respective condensers.