Surface elemental mapping using glow discharge—optical emission spectrometry

A glow discharge optical-emission spectrometry source was evaluated for use in imaging elemental surface distributions. A 1.8 cm2 area of a nickel–chromium alloy was sampled and copper emission was observed directly above the surface of a copper inclusion. By pulsing the glow discharge, the resolution was improved greatly over measurements using direct-current powering. Ranges of gas flows, pulse frequencies, pulse potentials, pulse widths, and pressures were explored to determine their effects on spatial resolution and were related to atom transport in the glow discharge cell. Pressure, pulse width, and pulse frequency were all found to have a significant effect on resolution.