Dispersion in the results of measuring the lifetime of negative ions due to their adsorption on ionization-chamber walls

Abstract

The time of extraction of negative ions from the ionization chamber of a static mass spectrometer has been measured as a value that significantly exceeds the time of their free exit from the chamber. It has been established that anomalously long ion extraction time is due to their adsorption on the ionization-chamber walls; as a result, their arrival at the analyzer tube is delayed. It has been shown that negative ions, which were initially generated as noninfinitely long-lived ones with respect to auto splitting off of an additional electron, are stabilized to everlasting ions due to adsorption, and the subsequent contribution from infinitely long-lived ions to the total ion flux reaching the recording system distorts the results of measuring the ion lifetime. It has been shown that some of the adsorbed ions are annihilated because of neutralization due to the additional electron tunneling to the surface. The probability of tunneling increases with an increase in temperature; thus, the temperature dependence of the ion lifetime is also distorted.