Evolution and evaluation of a jet-assisted glow discharge source for atomic emission spectrometry

Glow discharge atomic emission spectroscopy is a useful analytical method for the direct analysis of conducting solids thereby obviating the need for time-consuming and hazardous dissolution procedures common with other methods. Detection limits for analytical glow discharges, however, are restr...

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Main Author: Banks, Peter Robert
Format: Others
Language:English
Published: 2008
Online Access:http://hdl.handle.net/2429/2880
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spelling ndltd-UBC-oai-circle.library.ubc.ca-2429-28802018-01-05T17:31:03Z Evolution and evaluation of a jet-assisted glow discharge source for atomic emission spectrometry Banks, Peter Robert Glow discharge atomic emission spectroscopy is a useful analytical method for the direct analysis of conducting solids thereby obviating the need for time-consuming and hazardous dissolution procedures common with other methods. Detection limits for analytical glow discharges, however, are restricted to relatively high analyte concentrations when compared to other methods. One aspect of glow discharge sampling which proves adverse to analytical performance is through significant analyte loss before excitation by the re-deposition of sputtered species back onto the sample surface. Sputtered atoms are typically ejected from the sample surface with a range of energies that extends to 20 eV, however, this ejection energy is quickly thermalized by collisions with support gas species at pressures typically used for analyses. As a consequence, sputtered atoms are readily re-deposited back onto the sample surface, primarily due to diffusion. For a glow discharge using a planar diode electrode geometry, operating at pressures typically used for analytical purposes, up to 95 % of sputtered species re-deposit on the sample surface. Therefore, any method that retards re-deposition would significantly increase the atomization efficiency of glow discharges and increase the sensitivity of the technique. This work addresses the re-deposition problem using a jet assisted source that relies on a directed support gas flow that not only aids sample transport to the excitation region, but impedes re deposition. The original design has gone through a three-stage evolution: each stage correcting certain imbalances found for the previous model which culminates in an emission source capable of sub-ppm level limits of detection and a precision of less than 0.3 % for certain elements. A comprehensive study for the jet flow effects on the sample surface, using Scanning Electron Microscopy and Energy Dispersive X-ray Fluorescence, and the emitting plasma, using atomic emission and absorption spectroscopies, has been conducted. In addition, excitation processes have been studied in the jet-assisted plasma plume as it issues from the anode housing. Results indicate that the dominant atomic excitation process is through electron excitation. The electrons originate from the collision of two argon atoms which reside in metastable states. Science, Faculty of Chemistry, Department of Graduate 2008-12-12T21:18:01Z 2008-12-12T21:18:01Z 1992 1992-11 Text Thesis/Dissertation http://hdl.handle.net/2429/2880 eng 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. 4304095 bytes application/pdf
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language English
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description Glow discharge atomic emission spectroscopy is a useful analytical method for the direct analysis of conducting solids thereby obviating the need for time-consuming and hazardous dissolution procedures common with other methods. Detection limits for analytical glow discharges, however, are restricted to relatively high analyte concentrations when compared to other methods. One aspect of glow discharge sampling which proves adverse to analytical performance is through significant analyte loss before excitation by the re-deposition of sputtered species back onto the sample surface. Sputtered atoms are typically ejected from the sample surface with a range of energies that extends to 20 eV, however, this ejection energy is quickly thermalized by collisions with support gas species at pressures typically used for analyses. As a consequence, sputtered atoms are readily re-deposited back onto the sample surface, primarily due to diffusion. For a glow discharge using a planar diode electrode geometry, operating at pressures typically used for analytical purposes, up to 95 % of sputtered species re-deposit on the sample surface. Therefore, any method that retards re-deposition would significantly increase the atomization efficiency of glow discharges and increase the sensitivity of the technique. This work addresses the re-deposition problem using a jet assisted source that relies on a directed support gas flow that not only aids sample transport to the excitation region, but impedes re deposition. The original design has gone through a three-stage evolution: each stage correcting certain imbalances found for the previous model which culminates in an emission source capable of sub-ppm level limits of detection and a precision of less than 0.3 % for certain elements. A comprehensive study for the jet flow effects on the sample surface, using Scanning Electron Microscopy and Energy Dispersive X-ray Fluorescence, and the emitting plasma, using atomic emission and absorption spectroscopies, has been conducted. In addition, excitation processes have been studied in the jet-assisted plasma plume as it issues from the anode housing. Results indicate that the dominant atomic excitation process is through electron excitation. The electrons originate from the collision of two argon atoms which reside in metastable states. === Science, Faculty of === Chemistry, Department of === Graduate
author Banks, Peter Robert
spellingShingle Banks, Peter Robert
Evolution and evaluation of a jet-assisted glow discharge source for atomic emission spectrometry
author_facet Banks, Peter Robert
author_sort Banks, Peter Robert
title Evolution and evaluation of a jet-assisted glow discharge source for atomic emission spectrometry
title_short Evolution and evaluation of a jet-assisted glow discharge source for atomic emission spectrometry
title_full Evolution and evaluation of a jet-assisted glow discharge source for atomic emission spectrometry
title_fullStr Evolution and evaluation of a jet-assisted glow discharge source for atomic emission spectrometry
title_full_unstemmed Evolution and evaluation of a jet-assisted glow discharge source for atomic emission spectrometry
title_sort evolution and evaluation of a jet-assisted glow discharge source for atomic emission spectrometry
publishDate 2008
url http://hdl.handle.net/2429/2880
work_keys_str_mv AT bankspeterrobert evolutionandevaluationofajetassistedglowdischargesourceforatomicemissionspectrometry
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