Study on the Fluorescence Spectral Characteristics of Egyptian Blue
Mineral Pigment and Their Application in Development of Latent
Fingerprints
DAI Xue-jing1, TANG Cheng-qing2, LI Yun-peng1, SONG Jia1
1. College of Public Security Information Technology, Criminal Investigation Police University of China, Shenyang 110035, China
2. College of Forensic Sciences, Criminal Investigation Police University of China, Shenyang 110035, China
Abstract: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.
Key words:Fingerprint development; Egyptian blue mineral pigment; Near-infrared; Fluorescence; Background interference
代雪晶,汤澄清,李云鹏,宋 佳. 埃及蓝矿物质颜料荧光光谱测定及其在指印显现中的应用[J]. 光谱学与光谱分析, 2025, 45(05): 1383-1388.
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. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(05): 1383-1388.
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