The quantification of SIMS depth profiles by Maximum Entropy reconstruction
Allen, Paul Nicholas, 1968- (1994) The quantification of SIMS depth profiles by Maximum Entropy reconstruction. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b1416360~S15
The quantification procedures applied to raw SIMS data were devised on the basis of a simple model for the sputtering and ionisation that occur during measurement. The model and the associated quantification procedures have long been known to be inaccurate. If SIMS is to remain a useful analysis tool in the future, the quantification procedures must be adjusted such that current features of interest are accurately measured. This thesis describes the development of a more accurate (though empirical) model for the effects of the analysis, using the convolution integral. We propose a method for the quantification of SIMS depth profiles appropriate to this model, using Maximum Entropy (MaxEnt) reconstruction. SIMS depth profile data differ significantly from previous applications of the MaxEnt method: the very high signal to background ratio of the technique has lead users to plot the results on a logarithmic axis, giving much importance to extremely small signals. The noise on SIMS depth profiles has been characterised. A number of optimisation algorithms have been developed and tested, and the performance of the MaxEnt method on SIMS data has been assessed. A novel form of the entropy, particularly suited to SIMS depth profiles, has been suggested. This form has given excellent results.
|Item Type:||Thesis or Dissertation (PhD)|
|Subjects:||Q Science > QC Physics
Q Science > QD Chemistry
|Library of Congress Subject Headings (LCSH):||Secondary ion mass spectrometry -- Mathematical models, Maximum entropy method|
|Institution:||University of Warwick|
|Theses Department:||Department of Physics|
|Sponsors:||Science and Engineering Research Council (Great Britain) (SERC) ; Kratos|
|Extent:||xiv, 190 p.|
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