The effects of polymer pigmentation on fingermark development techniques.

Area of Science:

• Forensic Science
• Materials Science
• Surface Chemistry

Background:

• Latent fingerprint development relies on surface properties.
• Powder suspension techniques are increasingly used for print development.
• Titanium dioxide is a common white pigment found on various surfaces.

Purpose of the Study:

• To investigate the effect of titanium dioxide on carbon powder suspension fingerprint development.
• To understand the mechanism behind titanium dioxide's influence on powder adhesion.
• To compare the performance of carbon powder suspension with other development techniques in the presence of titanium dioxide.

Main Methods:

• Utilized scanning electron microscopy (SEM) to visualize powder adhesion.
• Employed secondary ion mass spectrometry (SIMS) to analyze surface composition.
• Tested carbon powder suspension, MoS2 small-particle reagent (SPR), and cyanoacrylate fuming on polymer substrates with and without titanium dioxide.

Main Results:

• Carbon powder suspension showed increased adhesion and staining on polymers containing titanium dioxide.
• SEM confirmed localized powder adhesion associated with titanium dioxide.
• SIMS indicated titanium dioxide's influence within the top 30 nm of the surface.
• The detrimental effect was not observed with MoS2 SPR or cyanoacrylate fuming.

Conclusions:

• Titanium dioxide detrimentally affects carbon powder suspension fingerprint development on polymers.
• The interaction is likely related to surface energy variations, independent of fingermark deposition.
• Alternative techniques like cyanoacrylate fuming are unaffected by titanium dioxide, offering better performance on contaminated surfaces.