A glow discharge time-of-flight mass spectrometry (GD-TOFMS) study of the ‘hydrogen effect’ using copper, iron and titanium cathodes

Sohail Mushtaq, Edward B. M. Steers, James A. Whitby, Peter Horvath, Johann Michler, Juliet C. Pickering
  • Journal of Analytical Atomic Spectrometry, January 2015, Royal Society of Chemistry
  • DOI: 10.1039/c5ja00112a

What is it about?

The main purpose of this paper is to understand the ‘hydrogen effects’ at very low hydrogen concentrations (0.01, 0.02, 0.03, 0.04, 0.06, 0.08, 0.1% v/v) in argon plasmas.

Why is it important?

Although much research work has been done on hydrogen in argon plasma and many papers have been published so far using both the OES and MS techniques, there are many unsolved questions regarding GD-MS investigations such as: - How do the concentrations of ions of analytical interest behave in dc GD-MS discharges when hydrogen is added in the low concentrations that would be expected in the analysis of typical samples? - How do the signals due to other relevant ions, e.g. Ar+, ArH+, behave at very low hydrogen concentrations? - What role do the doubly charged argon ions and dimer ions play in argon/ hydrogen plasmas? - How do complementary GD-MS results with standard GD-OES analytical conditions compare with trends observed with GD-OES studies and what information do they give about processes in the discharge itself? In this paper, we attempt to answer the above questions using studies on the effects of small amounts of added hydrogen in an argon plasma with a time-of-Fight mass spectrometer (TOFMS) for conditions common in GD-OES, i.e. a 4 mm diameter crater under constant voltage and current (700 V and 20 mA) conditions.

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http://dx.doi.org/10.1039/c5ja00112a

The following have contributed to this page: Dr SOHAIL MUSHTAQ