Activation of sub 2 nm singly charged particles with butanol vapors in a boosted 3776 TSI CPC

Ultrafine laminar TSI CPC based on the work of Stolzenburg and Mc Murry (1991) is widely used in aerosol science for the detection of particles down to 3 nm (D50 ~ 2.7 nm). This instrument uses butanol as working fluid. Di ethylene glycol (DEG) as working fluid has been introduced by Iida et al. 2011 for the activation and the growth of sub 3 nm particles without however giving detectable droplets with scattering light detectors. A second CPC is used as booster to count the DEG droplets. DEG presents on the other hand a high chemistry dependence to the activation and growth of particles. Butanol is known to present less chemistry dependence. This study focuses on the ability of butanol to activate and grow sub 3 nm positive particles in a commercial 3776 TSI CPC. The flowrate in the capillary is increased to minimize the losses. The temperature difference ΔT between the saturator and the condenser is increase to the limit of the homogeneous nucleation. The flowrate in the condenser and in the optical detector is kept constant and equal to 0.3 lpm. Tetra ethyl ammonium bromide positive monomer of 1.11 nm mobility diameter (0.81 nm mass diameter) is detected by the boosted instrument.