High resolution size analysis of nanoparticles and ions: running a Vienna DMA of near optimal length at Reynolds numbers up to 5000

A Vienna-type Differential Mobility Analyzer of near-optimal length fitted with a sheath air flow laminarizer is run at Reynolds numbers up to 5000, yielding record resolutions for nanoparticles. Full peak widths at half height of 2.7% are found at a mobility diameter below 2 nm (molecular ions of tetraoctyl ammonium). Particles with diameters as small as 1 nm may therefore be classified in this device with resolutions higher than previously attainable with much larger non-diffusing particles.