PENETRATION OF NANOMETER-SIZED AEROSOL-PARTICLES THROUGH WIRE SCREEN AND LAMINAR-FLOW TUBE

Penetration of nanometer-sized aerosol particles and ions through a si ngle wire screen and a laminar flow tube has been measured using a tan dem differential mobility analyzer system to accurately determine the size of the particles. The results obtained using a condensation nucle us counter as a particle detector showed that penetration of particles down to 2 nm in particle diameter follows the predictions of the theo ries of Cheng and Yeh and Gormley and Kennedy, This result suggests th at thermal rebound of particles on wire or tube surfaces does not occu r. The measured penetrations for negative ions smaller than 2 nm also agreed well with the theoretical predictions. In this case, however, c oncentration was measured with an electrometer, and there exists the p ossibility of electron transfer between the ions and the surfaces with out the (neutralized) ions being attached to them. (C) 1997 American A ssociation for Aerosol Research.