Sunlight-activated near-infrared phosphorescence as a viable means of latent fingermark visualisation.

The chromium-doped zinc gallogermanate, Zn3 Ga2 Ge2 O10 :0.5%Cr3+ , was prepared and modified for use as a near-infrared (NIR) luminescent fingerprint dusting powder. The optical properties of this material are illustrated and have been shown to offer versatility and promise in terms of overcoming troublesome backgrounds during latent fingermark examination and imaging. The highly fluorescent NIR emission of the powder allows inherently fluorescent and patterned substrate backgrounds to be mitigated, whilst the phosphorescent nature of the material allows all conceivable background interference to be removed, whilst also constituting the first reported use of a NIR phosphor for latent fingermark enhancement and imaging.