Study on the Fluorescence Spectral Characteristics of Vegetable Powders and Their Application in Development of Latent Fingerprints
DAI Xue-jing1, TANG Cheng-qing2, WANG Meng2, TONG Lin-dong1
1. Department of Audio and Video Examination, Criminal Investigation Police University of China, Shenyang 110035, China
2. Department of Trace Examination, Criminal Investigation Police University of China, Shenyang 110035, China
Abstract：It is an important basis for detecting cases to develop the latent fingerprints left on the substrates and make individual identification. Optical examination techniques which are nondestructive should be applied first when developing the latent fingerprints found at crime scenes. The practice shows that high contrast and fine ridge detailcan beobtained when applying optical examination techniques to develop the fingerprints on the most smooth substrates, while the physical and chemical methods are needed to develop the fingerprints on substrates of poor smoothness. Among them, the methods of powder dusting and fuming have been widely applied in the development of latent fingerprints. However, the long-term health of forensic technicians has been damaged seriously by most fluorescent powders and fuming materials.In addition,the most commonly employed fingerprint luminescent powders can fluoresce when excited with ultraviolet light. At the same time, the backgrounds can also fluoresce under the excitation of ultraviolet light, which results in low contrast between fingerprint and background. Therefore, it is an urgent task to find a low-cost, non-toxic, easy-to-operate, and widely used method for developing fingerprints. In this paper,the fluorescence characteristics of three non-toxic and inexpensive vegetable powders were studied to apply them to the development of fingerprints. Firstly, the fluorescence excitation spectrum and emission spectrum of three kinds of vegetable powders (broccoli powder, spinach powder and nori powder) were measured through fluorescence spectroscopy(FS). It was found that the fluorescence of broccoli powder was much stronger than that of spinach and nori powder by fluorescence measurement. Therefore, the broccoli powder was chosen to develop the latent fingerprints on trouble some substrates commonly encountered at crime scenes. The experiment results showed that: (1) All the three kinds of powders could fluoresce, and their peak fluorescence excitation wavelengths were all 417 nm, and the peak fluorescence emission wavelengths wereall 678 nm.Among the three kinds of powders, the emission intensity of broccoli powder was the highest. (2) In developing latent fingerprints on a range of highly patterned, colored non-porous and porous substrates，the broccoli powders could emit bright red fluorescence under violet 415 nm illumination. A narrow bandpass interference filter with a central wavelength of around 680 nm was used in front of the lens when photographing the fluorescent prints, and the results showed a high contrast between the fingerprint and the background with fine ridge detail and less interference. (3) Compared with the conventional luminescent powders, broccoli powder had higher development sensitivity. (4) Some backgrounds under violet 415 nm illumination could also fluoresce, but the background fluorescence was weak compared with the strong fluorescence of broccoli powders, revealing high contrast fingerprints with excellent ridge detail. (5) The fluorescence of the fingerprints on rough backgrounds created a sharp contrast, and the rough backgrounds did not interfere with fingerprint ridge, which was clear and coherent. (6) The commercially available broccoli powders used in the experiment had the characteristics of fine particles and strong adsorption ability, which could invoke favoured adhesion characteristics upon contact with fingerprint ridge residues, improving the sensitivity of fingerprint development.
代雪晶，汤澄清，王 猛，佟林东. 蔬菜粉末荧光光谱测定及其在手印显现中的应用[J]. 光谱学与光谱分析, 2022, 42(01): 158-163.
DAI Xue-jing, TANG Cheng-qing, WANG Meng, TONG Lin-dong. Study on the Fluorescence Spectral Characteristics of Vegetable Powders and Their Application in Development of Latent Fingerprints. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2022, 42(01): 158-163.
[1] Romain Steiner, Sebastien Moret, et al. Forensic Sci. Int.，2020, 314: 110411.
[2] Barros Hélio L, Stefani Valter. Forensic Sci. Int.，2016, 263: 83.
[3] Jo Dawkins, Lata Gautam, et al. Forensic Sci. Int.，2020, 309: 110186.
[4] Keith L Monson, Maria Antonia Roberts，et al. Forensic Sci. Int.，2019, 297: 111.
[5] Alfonso Bentolila, Ira Hartman, et al. Forensic Sci. Int., 2017, 278: 374.
[6] Annemieke van Dam, Maurice C G Aalders，et al. Forensic Sci. Int., 2016, 258: 19.
[7] Alicia Khuu, Xanthe Spindler, et al. Forensic Sci. Int., 2020, 309: 110185.
[8] Saif M, Shebl M, Nabeel A, et al. Sensor and Actuators B: Chemical, 2015, 220: 162.
[9] Ran X, Wang Z Z, Zhang Z J, et al. Chem. Commun., 2016, 52: 557.
[10] YU Ao-yang, YANG Rui-qin, WANG Meng(于遨洋，杨瑞琴，王 猛). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2018, 38(1): 144.
[11] Roberto S P King, Peter M Hallett, et al. Forensic Sci. Int., 2016, 262: e28.
[12] Maralee Tapps, Laurence McMullen, et al. Forensic Sci. Int., 2019, 300: e9.
[13] Wightman G F，Emery F，et al. Forensic Sci. Int., 2015, 249: 241.
[14] Florine Hallez, Pierre Ledroit, et al. Forensic Sci. Int.，2019, 298: 20.
[15] King R S P, Hallett P M, Foster D. Forensic Sci. Int.，2015, 249: e21.
