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Effect that the Relative Abundance of Copper Oxide and Zinc Oxide Corrosion has on the Visualization of Fingerprints Formed from Fingerprint Sweat Corrosion of Brass


  • John W. Bond D.Phil.

    1. Scientific Support Department, Northamptonshire Police, Wootton Hall, Northampton NN4 0JQ, U.K.
    2. Forensic Research Centre, University of Leicester, Leicester LE1 7EA, U.K.
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John W. Bond, D.Phil.
Scientific Support Department
Northamptonshire Police
Wootton Hall
Northampton NN4 0JQ


Abstract:  From an examination of the fingerprint sweat corrosion of 40 different individuals on α phase brass, we show that an increase in visualization can be achieved by applying a negative potential to the brass followed by the introduction of a conducting powder. Previously, this technique has been demonstrated only for a positive applied potential and a corrosion product that was dominated by p-type copper (I) oxide. X-ray photoelectron and Auger electron spectroscopic analyses of the surface of the corroded brass show that an increase in visualization with a negative applied potential corresponds with an increase in the concentration of n-type zinc oxide relative to p-type copper (I) oxide with the Cu:Zn ratio <0.8:1. Work function conditions for the formation of an n-type zinc oxide/brass rectifying Schottky barrier are fulfilled.