Theoretical modeling of sensitivity factors of Bayard-Alpert ionization gauges

Abstract

Measuring the relative sensitivity factors (Sr) in Bayard-Alpert ion gauge is technically demanding and time-consuming. Moreover, the accuracy deterioration in the low pressure range (high vacuum) becomes problematic. Experimental Sr values are reported for 91 molecules of diverse molecular structures. A three-descriptor QSPR model based on experimental data is established. The model obtained, which explains more than 93% of the data variance, has a good statistical validity and stability. The three selected molecular descriptors, Kier & Hall index, charge difference on the molecular surface, and count of H donor sites appropriately describe the physicochemical background of the relative sensitivity factors. The model developed in this work is freely accessible through the web: http://www.ut.ee/qsar.