The objectives of this work are twofold: firstly, to understand the inductively coupled argon plasma (icp) from a fundamental point of view and, secondly, to attempt to put that knowledge to practical use.
In an effort to realize this first objective, a simple two-level rate model was developed which allows the estimation of the deviations (due to radiative decay) of analyte level populations in the icp from local thermodynamic equilibrium (lte). The results were found to agree very well with experiment for analyte elements (Fe, Cr and Ba) which did not exhibit charge transfer with the argon support gas.
A comprehensive study of magnesium excited-state level populations was performed. It was found that charge transfer between argon ions and ground state magnesium atoms caused ionic magnesium to be overpopulated (with respect to the simple rate model calculations mentioned above). It was also found that, due to appreciable self-absorption, argon itself conforms to an lte model.
Electron temperatures (Te) were measured in the icp. It was found that, for electron densities greater than about 2x10¹⁵ cm⁻³, Te was within experimental uncertainty of the so-called lte temperature (Te,lte - calculated from the electron density). At lower electron densities, due to the large experimental errors involved, it was difficult to draw definitive conclusions regarding their agreement.
The plasma was also extensively characterized when an extra argon flow was added to the aerosol gas. It was found that at low values of the aerosol gas flow rate, mixing between it and the plasma gas was relatively complete, whereas at higher flow rates there was relatively little mixing. It was also found that the introduction of water into the plasma had a limited effect on sample excitation.
In order to fulfil the second objective, a method was developed to simulate emission spectra from an icp. The method involved the use of a computer program, which worked by combining basic physical data for atomic species, the results of icp fundamental studies, and a realistic instrumental line profile (described in detail). The method was used to simulate a hypothetical silver determination in NBS coal fly ash showing the effects of spectrometer bandpass, silver concentration, and line choice on spectral overlaps. / Science, Faculty of / Chemistry, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/30964 |
| Date | January 1990 |
| Creators | Burton, Lyle Lorrence |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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