Spectroscopy and Spectral Analysis, Volume. 45, Issue 5, 1383(2025)
Study on the Fluorescence Spectral Characteristics of Egyptian Blue Mineral Pigment and Their Application in Development of Latent Fingerprints
The development and identification of the fingerprints left by the suspects are the important basis for detecting cases. The majority of commercially available luminescent fingerprint powders can usually fluoresce upon excitation with ultraviolet (UV) light or blue and green light. Still, multi-colored and patterned backgrounds have intrinsic formulations (inks, binders, coatings, etc.), which also cause them to fluoresce within the same spectrum area. This creates a lack of distinguishing ability between the fluorescence of the developed latent fingerprint and the background. In addition, -most fluorescent powders have seriously damaged the long-term health of forensic technicians. Therefore, it is urgent to find a kind of non-toxic fluorescent fingerprint power suitable for use on substrates that are typically considered extremely difficult to treat. In this paper, the fluorescence properties of the natural Egyptian blue mineral pigment, which was harmless and cheap, were studied. The micro-morphology, crystal structure, luminescence properties, and surface functional groups of the Egyptian blue mineral pigment were characterized by scanning electron microscopy, X-ray diffractometer, fluorescence spectrophotometer, and Fourier transform infrared spectrometer. The Egyptian blue mineral pigment had good dispersion with anaverage diameter of about 1 μm, and its main component was a mixture of CuO and Cu2O. Under the excitation of 780 nm infrared, it could give strong emissions at the wavelength of 823 nm infrared. It was a silicate mixture containing copper ions. Finally, the Egyptian blue mineral pigment was used to develop the latent fingerprints on extremely troublesome substrates commonly encountered at crime scenes. The experimental results showed a high contrast between the fingerprint and the background with fine ridge detail and less interference. In addition, the excitation and emission spectra of the Egyptian blue mineral pigment were in the near-infrared region, which filled the blank of the method of developing fingerprints with fluorescence powders.
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DAI Xue-jing, TANG Cheng-qing, LI Yun-peng, SONG Jia. Study on the Fluorescence Spectral Characteristics of Egyptian Blue Mineral Pigment and Their Application in Development of Latent Fingerprints[J]. Spectroscopy and Spectral Analysis, 2025, 45(5): 1383
Received: Jun. 24, 2024
Accepted: May. 21, 2025
Published Online: May. 21, 2025
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