Penetration of nanometer-sized aerosol particles through wire screen and laminar flow tube

Penetration of nanometer-sized aerosol particles and ions through a single wire screen and a laminar flow tube has been measured using a tandem differential mobility analyzer system to accurately determine the size of the particles. The results obtained using a condensation nucleus counter as a particle detector showed that penetration of particles down to 2 nm in particle diameter follows the predictions of the theories of Cheng and Yeh and Gormley and Kennedy, This result suggests that thermal rebound of particles on wire or tube surfaces does not occur. The measured penetrations for negative ions smaller than 2 nm also agreed well with the theoretical predictions. In this case, however, concentration was measured with an electrometer, and there exists the possibility of electron transfer between the ions and the surfaces without the (neutralized) ions being attached to them. (C) 1997 American Association for Aerosol Research.