ISSN: 0022-1198
CODEN: JFSCA
Page Count: 11

Intramolecular Energy Transfer in the Europium-Ruhemann's Purple Complex: Application to Latent Fingerprint Detection
Menzel, ER
Director, Center for Forensic Studies, and professor, Physics Department, Texas Tech University, TX

Mitchell, KE
Graduate student, Texas Tech University, TX

(Received 19 November 1988; accepted 3 February 1989)

Abstract

The reaction product of ninhydrin with amino acids reacts further with europium chloride hexahydrate (EuCl³ · 6H²O) to form an organo-rare earth complex which exhibits Eu³⁺ luminescence at 615 nm with a lifetime of 0.4 ms. This emission is sensitized by intramolecular ligand to europium resonance energy transfer. Benzo(f)ninhydrin is better suited to this energy transfer process than ninhydrin and yields more intense Eu³⁺ emission. The emission is effectively excited by argon-ion laser near-ultraviolet (UV) light, which can be modulated such that time-resolved imaging can reveal amino acids on strongly fluorescent surfaces which would otherwise not be tractable. This is applied to the detection of latent fingerprints.

Keywords:
criminalistics, fingerprints, ninhydrin, benzo(f)ninhydrin, 5-methoxyninhydrin, europium chloride hexahydrate, fluorescence, time-resolved imaging, lasers, proximity-focused microchannel plate image intensifier

Paper ID: JFS12799J
DOI: 10.1520/JFS12799J
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