Fundamental investigations have been carried out on an Inductively Coupled Plasma (ICP) operated at 148 MHz, a frequency which is nearly three times higher than any previously reported for analytical ICPs used in spectrochemical analysis. High frequency operation is expected to provide easier sample introduction into the discharge, with a consequence of less energetic conditions in the central channel. Several plasma diagnostic techniques were employed in order to determine the conditions experienced by the analyte species in this source for spectrochemical analysis. Three different torch systems were investigated at 148 MHz and compared to the "standard" 27 MHz configuration. The highest excitation temperatures and electron densities were obtained in the 27 MHz configuration, and the lowest values in the largest torch at 148 MHz. Intermediate values were obtained in the intermediate-size torches at 148 MHz. These observations correlate reasonably well with the ratio of the plasma radius to the skin depth (r/s). The skin depth defines the region in which the majority of the electrical energy is deposited into the discharge, and is smaller at 148 MHz than at 27 MHz. The measurement of electron densities also allows the estimation of how closely a particular discharge approaches Local Thermal Equilibrium (LTE). As may be expected, LTE is most closely approached in the 27 MHz arrangement. The less energetic conditions characterized by lower temperatures and electron densities result in less intense analyte emission from the high frequency ICPs. Signal-to-Background ratios and detection limits reflect this trend, but the linearity of the calibration curves and freedom from vaporization interferences are not degraded. Finally, the introduction of organic solvents is much easier, and better detection limits in an organic matrix are obtained at 148 MHz. These investigations have shown the utility of classifying the effects of changing torch sizes and operating frequencies by means of the r/s ratio. This provides the analyst with a means of selecting the general range of conditions to be employed in a particular analysis.

No description available.

Thesis (PhD)--University of South Australia, 1999

Thesis (PhD)--University of South Australia, 1999

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 68-69).

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains v, 36 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 21).

Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2006. / "Title from dissertation home page (viewed June 28, 2007)." Source: Dissertation Abstracts International, Volume: 67-06, Section: B, page: 3105. Adviser: Gary M. Hieftje.

Bibliography: pages 46-50. / A sequential atomic emission spectrometer, using a low power (1,7 kW) argon-cooled inductively coupled plasma (ICP) system, was used for the determination of wear metals and additives in lubricating oils with xylene as solvent. The modified Simplex method was applied to establish the optimum experimental parameters for 21 individual spectral lines. The optimization was applied to single element analysis on the basis of net signal-to-background ratio (SBR) using the standard cross flow nebulizer and then repeated using the high solids Babington-type nebulizer. Weighted compromise conditions were calculated resulting in a maximum loss of 50% in the SBRs of the individual elements. These conditions result in an analytically useful plasma that gives low detection limits and high sensitivities for the analysis of metals in lubricating oils. Analytical parameters such as detection limit and analytical range for the analysis of 17 elements present in lubricating oil as wear metals or contaminants and 4 other elements present in the most common lubricating oil additives were determined. The detection limits reported here for oil in xylene are of the same order as the published limits for aqueous and for oil-in-MIBK solutions. However, the most valuable property of the ICP-AES was found to be the astounding analytical range which allows determinations to be made over a large concentration range without the need for serial dilutions. The effect of sample preparation was investigated by employing ultrasonic agitation prior to withdrawing the used oil from the sample vial. An upward trend was found in the element concentrations from manual shaking of the oil to ultrasonic agitation, indicating a particle distribution effect. Finally, the technique was tested successfully by analysing an NBS reference standard and by participating in several "round robin" used oil analyses. ICP-atomic emission spectrometry can be successfully applied to the analysis of metals in lubricating oils with a speed, accuracy and precision which at least equals, and even improves upon any other of the established techniques.

No description available.

Plasma oxidation, an alternative to combustion, is shown to be a non-destructive method for obtaining radiocarbon dates on perishable organic artifacts. Electrically excited oxygen gently converts organic carbon to carbon dioxide. Radiocarbon measurements are then performed using accelerator mass spectrometry. Because only sub-milligram amounts of material are removed from an artifact over its exposed surface, no visible change in fragile materials has been observed, even under magnification. Materials in this study include: Third International Radiocarbon Intercomparison (TIRI) sample B (Belfast pine); Fourth International Radiocarbon Intercomparison (FIRI) optional samples; six different materials from a naturally mummified baby bundle from southwest Texas; and peyote from Shumla Caves, Texas, and Cuatro Ci??negas, Mexico. Continuing previous research in the Rowe laboratory, a primary application of plasma oxidation has been its use to date rock art at archaeological sites around the world. This dissertation includes dates for: Toca do Serrote da Bastiana, Brazil; Ignatievskaya Cave, Russia; partially buried megalithic monuments, Spain; Arnold/Tainter Cave, Wisconsin; and Little Lost River Cave No. 1, Idaho.