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Title: Glow discharge mass spectrometry : source design and development, applications and theory
Author: Pichilingi, M.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1995
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Much of the work in this thesis was carried out with a strong regard for the interests of the collaborative body, British Steel Technical. Hence, an original review of the techniques employed for analysis within the steel industry are provided, which concludes outlining the potential role of GDMS. A new ion source was designed and constructed for coupling to an existing high resolution mass spectrometer for the analysis of flat samples by GDMS. Details of the extensive work carried out to improve and characterise this source are given. A new commercial instrument, the VG Gloquad, came onto the market during the course of this Ph.D. This instrument was used for comparison with our system and an evaluation of GDMS for analysis within the steel industry was performed. Results are given which demonstrate the potential of quadrupole-based GDMS for depth profiling. However, recommendations are given which could improve the performance of both state-of-the-art GDMS and GDOES. In addition, the theory of cathodic sputtering has been re-examined and an expression has been developed which describes the transport of sputtered material within the glow discharge. This predicts the inverse pressure dependence of glow discharge sputter yield observed, as well as its unexpected independence from the diffusion coefficient. It is also demonstrated that glow discharge sputter yield correlates well with the accepted theory for primary sputtering, as is also predicted by our expression, for both different discharge gases and sample targets. Finally, it is proposed that in the 1-3 Torr pressure range, typical for mass spectrometry, sputtering is due to bombardment by fast discharge gas atoms rather than discharge gas ions, as is the commonly held view. It is also being suggested that there is a change in mechanism at higher pressures to sputtering by ions of the sample itself.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available