Novel applications of signal processing techniques in atomic spectrometry: I. Tomographic investigations of atomic reservoirs. II. Instrumentation for monitoring magnetically-induced polarization rotation in atomic vapors. III. An investigation of the noi

Analytical chemists are concerned with making measurements which provide chemical information about a sample or an event. In many situations, the measured signal can be related directly to the desired information. Unfortunately, in other circumstances, an unwanted component (e.g., noise or a background signal) obscures the desired information. To obtain an accurate representation of the desired information, the analytical chemist must modify conditions or process data to discriminate against this undesirable clutter. In the work described here, three independent avenues of research were investigated as possible methods to isolate more efficiently the desired signal (information) in atomic spectrochemical analysis.;Fundamental studies of atomic reservoirs play an important role in identifying the chemical processes which influence analytical determinations. Identifying the spatial distribution of atomic species in these sources provides one important method whereby information about chemical interactions can be determined. To acquire these data, a new instrument was constructed which utilizes computed tomography (CT) image-reconstruction techniques to generate three-dimensional maps of emitting species in atomic sources. This CT instrument was used to determine the spatial distribution of the "easily ionized element emission interference" on the signal from an inductively-coupled plasma, and to provide new information about the chemical interactions which give rise to the interference.;The development of new instruments and techniques for trace-element determinations remains an area of active research in atomic spectrochemical research. One technique which has drawn increasing interest as a method for trace metal analysis is to monitor magnetically induced rotation of plane-polarized light by an atomic vapor. Atomic magneto-optic rotation spectrometry (AMORS) has previously been shown to provide a rapid and sensitive method for multi-element analysis. However, AMORS analysis, as traditionally practiced, suffers from many of the same spectral interferences experienced by atomic absorption spectrometry. Fortunately, many of the problems can be overcome by relatively simple signal-processing techniques. Instruments utilizing these new signal-detection schemes were constructed and evaluated. In general, these devices were shown to provide linear calibration curves, competitive limits of detection, and freedom from the deleterious effects of background interferences experienced by previous AMORS instruments.;In the third and final section of this research program, the noise spectral characteristics of an inductively coupled plasma mass spectrometer and a direct current plasma atomic emission spectrometer were determined. The noise spectra from both instruments were dominated by low-frequency noise (0-20 Hz) associated with drift in instrument components, and by audio-frequency noise (70-300 Hz) generated by instabilities in the support gases used for both sources. These data suggest that the precision of a measurement made with both instruments can be enhanced by simple changes in the geometry of the structures used to generate the plasmas.