Harnessing volatile luminescent lanthanide complexes to visualise latent fingermarks on nonporous surfaces

Abstract

Two commercially-available terbium and europium complexes, EuFOD and TbTMHD, provide luminescent visualisation of latent fingermarks placed on nonporous surfaces via sublimation. This is demonstrated using UV radiation from a forensic light source. The method was optimised on metal foil, with other archetypal nonporous surfaces (i.e. glass, ceramic) also suited to this method.

Metastable 9‐Fluorenone: Blueshifted Fluorescence, Single‐Crystal‐to‐Single‐Crystal Reactivity, and Evaluation as a Multimodal Fingermark Visualization Treatment

“…For this reason, new visualization methods that target the nonpolar components of fingermarks provide great interest to the forensic community. Our previous work has shown that sublimation can be harnessed to direct luminescent chemical reagents, for example, lanthanide complexes, into the lipid fraction of fingermarks to aid visualization . This work aims to complement the established fingermark visualization technique vacuum metal deposition (VMD), which is known for its high sensitivity and applicability across a wide range of surfaces .…”

“…While effective, the luminescent rare earth method to visualize fingermarks is not as cost‐effective as other strategies . By comparison, many small organic fluorophores are inexpensive, and offer a wide diversity of emission profiles spanning the visible spectrum.…”

“…Our previous work has shown that sublimationc an be harnessed to direct luminescent chemical reagents,f or example, lanthanide complexes, into the lipid fraction of fingermarks to aid visualization. [2] This work aims to complementt he established fingermark visualizationt echnique vacuum metal deposition (VMD), which is knownf or its high sensitivity and applicabilitya cross aw ide range of surfaces. [3] VMD could be improved by developing inherently luminescent fingermark coatings, as presently this is achieved by applyinga dditional treatments, such as fluorescents taining with Basic Yellow 40.…”

“…[4] Additional steps such as this complicate and lengthen the VMD process, and risk damaging the fragile fingermark evidence.While effective,t he luminescent rare earth method to visualize fingermarks is not as cost-effectivea so ther strategies. [1,2] By comparison, many small organic fluorophores are inexpensive, ando ffer aw ide diversity of emission profiless panning the visible spectrum.9 -Fluorenone is one such small organic fluorophore, and it forms the basis of many luminescent moleculard evices and materials. This is exemplified by fluorenone scaffolds found in light-emittingd iodes, [5] charge-transfer compounds, [6] copolymers, [7] devices for studying protein-ligand interactions, [8] and organic solar cells.…”

“…[13] Thisw avelength range is ideal for forensic applications because it spans the optimal detection range of the humane ye. [16] Thep hysical properties of 9-fluorenone are similarly interesting, with as ublimation vapor pressure of 0.0121Paa nd an enthalpy of sublimation of 88.5 AE 3.7 kJ mol À1 at 300 K, [17] and suggest that sublimation represents av iable vectoro fd elivery into al atent fingerprint.Given the well-documentedp hysicalp roperties of 9-fluorenone,a nd an established protocol for delivery of volatile species into fingermark residues, [2] work began by applyingf luorenone using this prior protocol. Uptakeo f9 -fluorenone into the fingermark was apparent even without optimizing the heating and vacuum conditions (Figure 1; details of the fingermark study and subsequent visualization conditions are listed in the Supporting Information).…”