DESIGN AND CHARACTERIZATION OF A RADIO-FREQUENCY-POWERED GLOW-DISCHARGE SOURCE FOR DOUBLE-FOCUSING MASS SPECTROMETERS

A radio-frequency- (rf-) powered glow discharge has been interfaced to a double-focusing mass spectrometer. This type of discharge allows direct analysis of nonconducting, as well as conducting, solids. The rf discharge source and electrical system overcome several problems which have inhibited success in prior efforts. Problems of inadequate rf shielding, maintaining the necessary dc bias potential on the sample surface, preventing rf modulation of ion energies, and coupling of the accelerating potential to the discharge are resolved. Representative spectra of glass, soil, and brass matrices are presented. Preliminary relative sensitivity factors for conducting and non-conducting matrices show relatively small differences in ion yields across the periodic table.