Monodisperse nanometer size silver particles as small as 1 nm were generated by a new differential mobility analyzer and an IR ray furnace at a concentration higher than 10(3) cm(-3). The test nanometer size particles were introduced into stainless steel wire screens and circular aluminum tubes to investigate the particle rebound on solid surfaces. As a result, it was found that the particle rebound may increase the particles penetration through circular tubes when the particles are smaller than 2 nm.