Investigations of the effect of hydrogen in an argon glow discharge

Clear evidence of the effects caused by hydrogen, introduced in different f orms in an analytical glow discharge source (GDS) operated with argon, is p resented for the different matrix elements copper, stainless steel, titaniu m, aluminium and silicon. When hydrogen is present even in small quantities in argon, not only are there significant changes in the emission line inte nsities of most elements (analyte and plasma species), but also new spectra l features, such as emission bands of new compounds (hydrides of sputtered sample constituents) and a continuous background in the range similar to 22 0-440 nm. Moreover, the discharge current (the dependent parameter in our e xperiments) decreases with increasing hydrogen concentration. Different mod es of hydrogen introduction, externally in gaseous form or sputtered as a s ample constituent, cause very similar effects in terms of discharge current , line intensity (of analyte and plasma gas) and emission continua, which i mplies similar changes in the discharge processes in the two cases. The exc itation of the hydrogen continuum appears to quench the population of the a rgon metastables (11.55 and 11.72 eV) and, consequently, other elementary p rocesses in the plasma in which the argon metastables take part, but to a d ifferent extent for each analyte.