Fig. 4.
Appearance times of neutral plus charged clusters from the PSM (black circles) and of negatively charged clusters from the APi-TOF (blue circles) and an air ion spectrometer that measures ion mobility directly (AIS, blue diamonds), for the beginning of an example new particle formation experiment, initiated by UV illumination. Vertical error bars correspond to deviations in assumed densities by ±200 kg⋅m−3 (APi-TOF), the range of cutoff diameters in instrument calibrations (PSM, ±0.2 nm), or the widths of size channels (AIS, ±7%). The vertical bars show when the high-voltage clearing field in the CLOUD chamber was turned off (red) and when the UV lights in the CLOUD chamber were turned on (purple).