New μs-pulsed DC glow discharge assembly on a fast flow high power source for time resolved analysis in high resolution mass spectrometry

Abstract

A new μs-pulsed dc glow discharge assembly on a fast flow high power source attached to a high resolution mass spectrometer, has been successfully developed for time resolved measurements and thin film analysis. The glow discharge characteristics and the temporal profile evolution behaviours have been investigated with a copper sample. The impacts of pulse width (12 μs–75 μs), pulse voltage (600 V to 1000 V) and argon flow rate (175 sccm–700 sccm) on the glow current, matrix ion and argon ion intensities have been evaluated. Factors pertinent to the temporal profile characteristics including the time of flight of analyte ions travelling from the sample surface to MS analyser and the Penning ionisation process were discussed. This new assembly allows sub-micrometre layer analysis for depth profiling of thin layered structures such as photovoltaic films, with significantly improved depth resolution and increased matrix ion signal to background noise ratios.