基于YVO4∶Eu纳米发光材料的足迹增强显现

Enhanced Development of Footprints Using YVO4∶Eu Luminescent Nanomaterials

足迹显现技术一直是刑事科学技术领域中的关键技术之一,也是足迹分析与足迹鉴定的重要前提。本研究在借鉴手印纳米荧光显现技术先进研究成果的基础上,提出了基于YVO4∶Eu纳米发光材料的足迹增强显现技术,旨在改善提升足迹的显现效果。以稀土硝酸盐和原钒酸钠为原料、柠檬酸三钠为表面修饰剂,利用水热法合成出适于足迹显现的YVO4∶Eu纳米发光材料。采用透射电子显微镜、X射线衍射谱、紫外可见吸收光谱、荧光光谱、傅里叶变换红外光谱对该纳米发光材料的微观形貌、晶体结构、吸收性质、发光性能、表面基团进行表征。所合成的YVO4∶Eu纳米发光材料其微观形貌为类球形、平均粒径为39.2 nm,其晶体结构为四方晶系,紫外最强吸收波长为257 nm,在254 nm紫外光激发下能够发射614 nm红色可见光,表面为柠檬酸分子修饰。研究最终将YVO4∶Eu纳米发光材料应用于赤足足迹和穿鞋足迹的增强显现技术,并详细探讨了两种类型足迹的粉末法显现原理。赤足足迹显现结果表明,足迹的形态轮廓分明,乳突纹线连贯,细节特征明显,屈肌褶纹、脱皮、附着物等特征反映明显;穿鞋足迹显现结果表明,足迹的鞋底花纹特征完整明显,以上显现痕迹特征均能够达到足迹检验鉴定的要求。另外,该研究分别探讨了纳米材料的发光性能、颗粒尺寸、微观形貌对于提高足迹显现对比度、灵敏度、选择性的具体作用。该研究提出的基于YVO4∶Eu纳米发光材料的足迹增强显现技术具有对比度强、灵敏度高、选择性好等一系列显著优势,为稀土发光纳米材料的研究拓展了应用范围,也为足迹显现传统方法的发展提供了创新思路。

Footprint development has long been considered as one of the essential technologies in forensic sciences,which is an important prerequisite for footprint analysis and footprint identification.On the basis of our previous research achievements in nanomaterial based development of latent fingerprints,in this paper,we put forward an enhanced development of footprints using YVO4∶Eu luminescent nanomaterials(NMs)in order to improve the results of footprint development greatly.Firstly,YVO4∶Eu luminescent NMs were synthesized via a typical hydrothermal method,using rare earth nitrate and sodium orthovanadate as the raw materials,and trisodium citrate as the modifier.Then,the micromorphology,crystal structure,ultraviolet absorption property,luminescent performance and surface functional groups of synthesized NMs were characterized by transmission electron microscopy,powder Xray diffractometer,ultravioletvisible spectrophotometer,fluorescence spectrophotometer and Fourier transform infrared spectrometer,respectively.The YVO4∶Eu luminescent NMs were quasispherical in shape with an average diameter of 39.2 nm and had a tetragonal crystal structure.The maximum ultraviolet absorption wavelength of the NMs was 257 nm.Under a 254 nm ultraviolet excitation,they could give strong red emissions at a wavelength of 614 nm.The NMs were modified with citric acid molecules on the surface.Finally,the YVO4∶Eu luminescent NMs were used for enhanced development of barefoot and footwear impressions.The mechanisms for two types of footprint development were also discussed in detail.The barefoot development results showed that the morphological features were sharp,the friction ridge was coherent,and the detailed features were clear,and the folds,exfoliation and coherent substance were obvious.The footwear development results showed that the footwear pattern features were intact and distinct.The developed footprint features could fully meet the main requirements in footprint examination and identification.In addition,the promotion effects of luminescent property,particle size and micromorphology of synthesized NMs on the contrast,sensitivity and selectivity in footprint development were also discussed.Our enhanced development of footprints based on YVO4∶Eu luminescent NMs has a series of advantages including strong contrast,high sensitivity and good selectivity,which will not only expand the applications of rare earth luminescent NMs but also provide innovative ideas for traditional footprint developing methods.