The optogalvanic effect : pulsed signal collection for laser-enhanced ionization and optogalvanic resonance detection of atomic and molecular absorption
Electrical interferences arising from concomitants with low ionization potentials have complicated the determination of trace metals by laser-enhanced ionization (LEI). The potential and field relationships have been examined for the non-intrusive split cathode/burner head anode electrode configuration and pulsed signal collection has been investigated as a remedy for electrical interferences. LEI signal enhancement and supression have been related to changes in the electric field since the current through a flame in proportional to the electric field present. Time-resolved signal recovery has been demonstrated as an instrumental method for discriminating against electrical interferences in LEI spectrometry. Resonance detection and quantification of atomic and molecular absorption have been demonstrated for Na, Cu, Li, and I(,2) using the optogalvanic effect. A pulsed dye laser tuned to an absorption transition of the analyte was directed through the analyte vapor in a flame or absorption cell then into a discharge tube containing the analyte. The optogalvanic signal was monitored and related to the analyte concentration. Though this technique does not compete with other spectroscopic techniques for low detection limits, special cases where an instrument will be dedicated to a routine determination, requiring a simple, inexpensive, robust detector with high resolution, would lend itself to OG detection. Design modifications are suggested for achieving lower detection limits
Hochschulschrift, English, 1983