An alternative method for determining the transmission function of secondary ion mass spectrometers

Abstract

The transmission function of our secondary ion mass spectrometer is determined from the trajectories of secondary ions emitted from the target surface to the analyzer through the use of SIMION software. The transmission function (T(E)) is found to have a power law dependence on the emission energies (E) of the secondary ions, in the form T(E) α E-β with β = 1.53 ± 0.02. This agrees well with the value of β = 1.50 ± 0.01 obtained experimentally by sputtering K+ ions from a Cu target. This observation shows that K atoms are sputtered off mainly as charged particles, a condition that is consistent with the electron tunneling model. The method described in this paper can be used to determine the transmission function for both positive and negative secondary ions in any mass spectrometer with an electrostatic or magnetic analyzer. © 1995.