Abstract:

The use of fluorescent materials for latent fingerprint imaging on the surface with background fluorescence has defects such as poor contrast, low sensitivity and poor visualization effect, while the long-lived luminescence properties of phosphorescent carbon nanomaterials can effectively eliminate interference of background fluorescence in development of latent fingerprints. Therefore, finding the phosphorescent carbon nanomaterials with convenient preparation and non-fluorescent interference development of latent fingerprints is of good importance. In this work, phosphorescent carbon nanoparticles (CNPs) powder was prepared through low-temperature pyrolysis procedure with boric acid matrix-assisted synthesis using diethylenetriamine and phosphoric acid as precursors. The as-prepared phosphorescent powder was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible absorption spectroscopy (UV-vis) and photoluminescence spectra. The results indicated that prepared CNPs powder was graphite-like structure, sphere⁃like in shape with good dispersibility and rich in functional groups on the surface. The obtained CNPs powder emitted bright blue fluorescence under excitation with 365nm ultraviolet light, and then turning off the excitation source, the strong green phosphorescence of CNPs powder was observed for up to 10s. The synthesized CNPs powder was applied for developing latent fingerprints on substrates with background fluorescence. For single and complex overlapping latent fingerprints on strong fluorescent substrates, developed clear phosphorescent fingerprint patterns with coherent ridges, strong contrast and well-defined details could be observed by using CNPs powder. The method proposed based on phosphorescent CNPs powder could effectively eliminate interference from intense background fluorescence, achieving fluorescence-free visualization of latent fingerprints.

Key words: phosphorescence, carbon nanomaterials, nanoparticles, latent fingerprints, fingerprint development

摘要：

利用荧光材料显现具有背景荧光客体表面的潜在手印存在对比度差、灵敏度低、显现效果不佳等缺陷，而磷光碳纳米材料的长寿命发光特性能够在潜在手印显现中有效避免背景荧光干扰。因此，开发一种制备简便快捷且能实现潜在手印无荧光干扰高质量显现的磷光碳纳米材料具有重要意义。本研究以二乙烯三胺和磷酸为前体，通过低温热分解反应并结合硼酸基质辅助合成法制备了磷光碳纳米颗粒（CNP）粉末。利用X射线衍射（XRD）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、紫外可见（UV⁃vis）吸收光谱和光致发光光谱对制备的CNP粉末进行了表征。结果显示，CNP粉末具有类石墨结构，形貌为类球形颗粒，分散良好，表面含有丰富的官能团。CNP粉末在365nm紫外灯照射下呈现明亮的蓝色荧光，关闭激发光源后，立即呈现长达10s的绿色室温磷光。基于合成的CNP粉末的磷光特性，将其应用于荧光客体表面潜在手印的显现研究。对强荧光发射客体表面潜在手印的显现结果表明，单一手印和复杂的重叠手印经CNP粉末显现后都呈现出清晰明亮的磷光手印图谱，手印纹路连贯、背景反差大、细节特征显著。利用磷光CNP粉末进行手印显现能有效消除强烈的背景荧光干扰，实现潜在手印的无荧光干扰显现。

关键词: 磷光, 碳纳米材料, 纳米粒子, 潜在手印, 手印显现