Sampling and Analytical Characteristics of an Electrically Vaporized Thin-Film Plasma in an External Magnetic Field

Abstract

A magnetic field of a few kilogauss oriented normal to the electric field in the plasma generated by a capacitive discharge through a thin silver film is used to obtain an ExB drift motion of the plasma. The plasma current is used to generate the magnetic field in a coil surrounding the plasma. The plasma drift motion is used to confine the plasma to the region near the surface of the plastic substrate which originally supported the thin film and the powder or solution residue sample. The result is greater interaction of the plasma with the sample, as illustrated by more rapid vaporization of the sample, reduced effects of particle size on analyte radiation intensity, and significantly improved shot-to-shot reproducibility. While analyte line intensities frequently are lower in the ExB plasma, line-to-background intensity ratios may be greater if an optical mask is used to block radiation near the substrate surface.