Mass spectrometric sampling through a small hole in the adiabatic flow region

Abstract

This paper describes a simple theoretical treatment of sampling by a mass spectrometer through a pinhole at pressures for which the mean free path of the molecules is small compared with the diameter of the hole. An expression has been derived which relates the ion beam intensity to the partial pressures of the components of a mixture on the high-pressure side of the sampling pinhole. Experiments have been carried out to test the validity of the theoretical expression; its applications to the analysis of chemically reacting and other systems have also been discussed.