Empirical methods for determination of ionization gauge relative sensitivities for different gases

Abstract

The relative sensitivities of a Bayard-Alpert ionization gauge for various organic molecules have been measured. There is a good correlation with total ionization cross section at 75 eV. For monofunctional compounds a correlation with number of electrons is seen with different functional groups on different lines. The best general correlation is with the polarizability, α, with R x=0.36 α +0.30, where R x is the chemical sensitivity relative to N 2=1.00. Alkanes and the noble gases have slightly larger R x values than predicted by this equation.