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The most difficult issue as regards hydrogen (H) analysis using the laser-induced plasma technique is the disturbance of H emission by H2O molecules. This problem is essentially solved in this paper by employing a novel technique that makes use of the specific characteristics of a TEA CO2laser. Thus, a small helium gas plasma was produced by focusing a TEA CO2laser onto a zircaloy surface containing H atoms. High-purity helium (He) gas was passed over the focusing point during the experiment so that the plasma was totally covered by the He gas and the H2O molecules remaining in the surrounding gas could not attack the plasma region. This technique ensures that only hydrogen atoms come out from the melted region of the sample surface, and are excited viametastable He atoms. This method has allowed us to confirm that H alpha (Hα), H beta (Hβ), H gamma (Hγ), and H delta (Hδ) emission can clearly be detected from a hydrogen-containing zircaloy sample with no interference from host emission lines or the H emission arising from H2O. The intensity ratio of Hα, Hβ, and Hγwas compared with that obtained for a low pressure hydrogen discharge lamp. [ABSTRACT FROM AUTHOR]

It is now well known that traces of molecular gases such as hydrogen or nitrogen can affect significantly the electrical characteristics, sputtering rates and relative intensities of emission lines in glow discharge optical emission spectrometry (GD-OES). These changes, caused by the molecular gases which are very often present in the discharge for various reasons, have a serious impact on the accuracy of analytical results. Therefore, it is important to describe these effects in detail and to try to understand the processes involved. The results presented in this paper focus on the effects of hydrogen and nitrogen on intensities of atomic emission lines of iron and titanium. In the case of hydrogen, when intensity ratios (intensities measured in argon–hydrogen relative to those measured in pure argon) are plotted against the excitation energies of the lines, these intensity ratios increase with the excitation energy between approx. 3 and 5 eV for both elements studied. Furthermore, in the case of iron, several emission lines with the excitation energy between 5.3 and 5.6 eV are strongly enhanced in the presence of hydrogen. It has been also observed that this effect is more pronounced at lower currents. On the other hand, it has been found that nitrogen does not have any similar effect: the gradient of the intensity ratios of both elements is negligible or even negative and no emission lines are enhanced in the presence of nitrogen. A comparison was also made between direct current and radiofrequency powered glow discharges and very similar trends have been obtained. [ABSTRACT FROM AUTHOR]