Vacuum metal deposition: developing latent fingerprints on polyethylene substrates after the deposition of excess gold

A previously identified difficulty with the development of latent fingerprints on low-density polyethylene (LDPE) by vacuum metal deposition (VMD) is that excess gold deposition prevents effective zinc deposition and so inhibits latent print development [1]. The investigation of a means to correct f...

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Bibliographic Details
Published in:Forensic science international 2001-11, Vol.123 (1), p.5-12
Main Authors: Jones, Naomi, Stoilovic, Milutin, Lennard, Chris, Roux, Claude
Format: Article
Language:English
Subjects:
Applied sciences
Cadmium
Clusters
Coating, metallization, dyeing
Deposition
Dermatoglyphics
Exact sciences and technology
Experiments
Fingerprint detection
Fingerprints
Forensic Medicine - methods
Forensic sciences
Gold
Gold deposition
Humans
Latent fingerprints
Low density polyethylenes
Machinery and processing
Plastics
Pollutant deposition
Polyethylene
Polymer industry, paints, wood
Spectrum analysis
Substrates
Technology of polymers
Vacuum
Vacuum chambers
Vacuum metal deposition (VMD)
X-rays
Zinc
Zinc deposition
Zinc oxide
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Summary:A previously identified difficulty with the development of latent fingerprints on low-density polyethylene (LDPE) by vacuum metal deposition (VMD) is that excess gold deposition prevents effective zinc deposition and so inhibits latent print development [1]. The investigation of a means to correct for excess gold deposition was the basis for this study. Exposure to zinc and the readmission of air into the vacuum chamber followed by VMD development results in the deactivation of the initial gold clusters due to the formation of zinc oxide and the adsorption of air and water molecules. As a result, the majority of the gold deposited during the second treatment creates new gold clusters rather than adding to the gold clusters previously formed. After excess gold deposition on LDPE, the deposition of 1.5 times the optimum gold amount will result in good-quality normal development. The results also indicate that, on all surfaces, at least twice the initial gold count should be used for re-treatment when further development is required after air has been readmitted to the chamber.
ISSN:0379-0738
1872-6283
DOI:10.1016/S0379-0738(01)00507-2