Publication
The accurate measurement of aerosol particles and clusters smaller than 3 nm in diameter is crucial for the understanding of new particle formation processes. The particle counters used for measuring these particles are typically calibrated with metal or salt particles under dry conditions, which does not always represent the field conditions where these instruments are later used. In this study, we calibrated the All nano Condensation Nucleus Counter (nCNC), consisting of the PSM (Particle Size Magnifier) and a laminar flow butanol based CPC (Condensational Particle Counter), with well-defined biogenic oxidation products from beta-caryophyllene oxidation and compared it to a calibration with tungsten oxide under the same conditions. The organic particles were detected less efficiently than the inorganic ones. This resulted in a higher cut-off size for beta-caryophyllene oxidation products than for tungsten oxide. At the same PSM settings, the cut-off size for tungsten oxide was 1.2 nm and for beta-caryophyllene oxidation products 1.9 nm. However, repeating the calibration of the biogenic particles at 13% relative humidity at 31 degrees C, increased their detection efficiency in the PSM, increasing the cut-off diameter to 1.6 nm.