[A study of developing fingermarks by nano-titanium dioxide shielding ultraviolet-ray].

In view of the difficulty in developing fingermarks on the color or strong fluorescence surface, the present paper reported a novel method to develop fingermark by shielding ultraviolet-ray. Nano-titanium dioxide with rutile phase had extremely high shielding ability of ultraviolet-ray. The TEM indicated that the average particle size of rutile titanium dioxide in experiment was about 30 nm, and they were mostly sphericity. The UV-Vis spectra indicated that the rutile nanoparticles shield UV with wavelength less than 400 nm. The rutile nanoparticles were physically adsorbed on the ridges of fingermarks on the color or strong fluorescence surface adequately and were not or a little adsorbed on the object surface by dusting or shaking. The ridges of the developed fingermarks were dark and the background was light under irradiation of 365 nm. We could obtain good images, and the contrast of lightness between the ridge and the background was obvious. In contrast to traditional developing technique-superglue fuming-Rhodamine 6G (or BBD) dyeing strengthening technique, the effect of nano-titanium dioxide shielding ultraviolet-ray detection technique was better. By the new detection technique, the ridges of the developed fingermarks were smooth and the detail characteristics of the developed fingermarkes were clear. The research results indicate that the nano-titanium dioxide particle is an effective and convenient developer of fingermark on the color or strong-fluorescence or color-strong fluorescence surface under irradiation of 365 nm with its shielding ultraviolet-ray property. Especially, the developer also has quite satisfactory effect on old fingermarks on the non-porous objects in contrast to traditional methods. The new detection technique is convenient, efficient, fast, and economical and has a wide application foreground in the field of fingermark developing.