Suppression of molecular ions in secondary ion mass spectra

摘要

A method of suppressing molecular ions in the secondary ion mass spectra of conducting, semiconducting and insulating specimens is described using a commercial secondary ion microscope/mass analyzer with unconventional primary beam conditions and uncoated samples, so as to almost eliminate the contribution of molecular ions to the mass spectrum. This results in excellent discrimination for major and trace element detection in these materials, including for example complete resolution of the rare earth elements in a number of minerals. Complete elemental analysis for a much enhanced range of elements down to the ppb level is now possible. The method also facilitates the analysis of insulating materials which would undergo surface charging distortion under any other condition.