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An experimental study was conducted in search of the experimental condition required for the much needed suppression of spectral interference caused by surface water in hydrogen analysis using laser-induced low-pressure helium plasma spectroscopy. The problem arising from the difficulty in distinguishing hydrogen emission from hydrogen impurity inside the sample and that coming from the water molecules was overcome by taking advantage of similar emission characteristics shared by hydrogen and deuterium demonstrated in this experiment by the distinct time-dependent and pressure-dependent variations of the D and H emission intensifies from the D-doped zircaloy-4 samples. This similarity allows the study of H impurity emission in terms of D emission from the D-doped samples and thereby separating it from the H emission originating from the water molecules. Employing this strategy has allowed us to achieve the large suppression of water induced spectral interference from the previous minimum of 400 [micro]g/g to the current value of 30 [micro]/g when a laser beam of 34 mJ under tight focusing condition was employed. Along with this favorable result, this experimental condition has also provided a much better (about 6-fold higher) spatial resolution, although these results were achieved at the expense of reducing the linear calibration range from the previous 4 300 [micro]g/g to the present 200 [micro]g/g.

It was proved that the analysis of deuterium can be conducted using laser-induced plasma spectroscopy. By selecting the appropriate surrounding gas, its pressure, and gating time of the detection system, it was shown that the emission lines of both hydrogen ([H.sub.[alpha]]) and deuterium ([D.sub.[alpha]]), separated by only 0.179 nm, can be fully resolved. A linear calibration curve was also obtained, indicating that this technique has the potential for quantitative analysis of deuterium. The minimum detection limit achieved in this stage of research was estimated to be 50 ppm. We have also shown that this technique can be used as a simple and rapid method for D and H analysis in solid samples.

An Nd-YAG laser was focused on various types of solid organic samples coated on the surface of a glass substrate surrounding air pressure of 2 Torr and a modulated technique was used to study the mechanism of excitation of the emission of the organic material. The results showed that ablated atoms and molecules are excited by a shock-wave mechanism.

Several experimental studies are conducted to explain the spatial densities and the intensity distribution of the enhanced hydrogen emission from low-pressure He plasmas. A new mechanism describing the contribution of helium metastable excited state to the experimental phenomenon is also discussed.

A series of measurements were performed on the time dependences of the intensities of helium, hydrogen, and deuterium emission lines from the corresponding laser-induced helium plasma at atmospheric pressure for two different He flow rates is presented. The resolved [H.sub.[alpha]] and [D.sub.[alpha]] emission lines demonstrated the benefits of He-assisted delayed excitation of H and D atoms and the enhanced intensity and lifetime at a high He flow rate.

The [N.sub.2]-induced quenching of He-induced intensity enhancement effect is studied in reduced-pressure plasma emission produced by Nd-YAG irradiation on solid zircaloy and porous fossil samples. The quenching effect is explained as a consequence of energy depletion of the He metastable excited state triggered by the Penning ionization process induced by the presence of nitrogen.

A study on gas analysis by means of laser-induced breakdown spectroscopy is conducted using a Nd-yttrium aluminum garnet laser and helium host gas at atmospheric pressure on a sample of mixed water (H2O) and heavy water (D2O) in vapor form. It is argued that the helium metastable excited state plays an important role in the hydrogen excitation process.

The possibility of determinating carbon and hydrogen in fossil samples using low pressure plasma were demonstrated and the samples were collected from the Sangiran region, located some 15 km north of Surakarta, central Java, Indonesia. Carbon emission was found to decrease significantly with the degree of fossilization and no carbon emission was found in a horn fossil dated at 1x10(super 6) yr.