Metal-vapor vacuum arc as a primary ion source for secondary ion mass spectrometry

A novel secondary ion mass spectrometry (SIMS) ion source, MicroMEVVA, introduces multiply charged primary ions such as Fe2+, Ta(2–4)+, W(2–6)+, and Pb2+ into a Fourier-transform mass spectrometer to give about 50 μA cm−2 current densities at the sample. Its ion accelerating potential of 11 kV thus makes possible a maximum ion energy of 66 keV. The effiency for desorption ionization of crystals violet and gramicidin S is greatly increased by changing from 17 to 38 keV primary ion energy and from 10 to 1 μs ion pulse duration, but is affected less by ion mass. Reactions between tungsten ions and neutral molecules show an increasing cross-section for charge exchange with increasing ion charge; only W+ participates in ion/molecule reactions with chlorotrimethylsilane.