It is difficult to detect particles smaller than 2 nm in diameter, however, it is possible to grow them so that they are optically detectable. For particles larger than 2-3 nm, it is possible to enlarge them by condensation of an alcohol, e.g. butanol, or water. For the smallest of particles, this is, however, not possible. A nano condensation nucleus counter (nCNC) consists of a particle size magnifier (PSM) and a condensation particle counter (CPC). Often the nCNC is denoted the PSM, but it is comprised of two instruments. In the PSM, particles with a diameter of 1-90 nm are enlarged to around 90 nm by condensation of diethylene glycol. In the following butanol-operated CPC, the particles are enlarged by butanol until they reach a size where they are optically detectable.