LaPO_4∶Ce,Tb纳米荧光粉末的合成及其在指纹无损显现中的应用

采用溶剂热法在水和乙二醇的混合溶剂中合成出了高质量的LaPO_4∶Ce,Tb纳米荧光粉末。然后通过透射电子显微镜(TEM)、粉末X射线衍射(XRD)、荧光光谱(FS)等表征手段分别对稀土纳米荧光粉末的微观形貌、晶体类型、荧光性能进行了表征,合成纳米荧光粉末的形貌为单分散的纳米棒,平均长度为700nm、平均直径为20nm,其晶体结构为单斜LaPO_4晶型,并且在254nm紫外光照射下能够产生较强的绿色荧光。最后将合成的纳米荧光粉末应用于光滑客体表面汗潜指纹的无损显现中,并详细考察了指纹显现的对比度、灵敏度、选择性、背景干扰等指标。实验结果表明,使用LaPO_4∶Ce,Tb纳米荧光粉末显现的指纹在254nm紫外光的激发下能够产生明亮的绿色荧光,指纹乳突纹线部位连贯清晰、细微特征反映明显,指纹与客体之间的对比反差强烈、客体产生的背景干扰较小,因此该显现方法具有较高的对比度、灵敏度和选择性。本显现方法具有操作方法简单、显现效果优良、适用范围广泛等优点。本研究的重要创新之处在于,经LaPO_4∶Ce,Tb纳米荧光粉末显现后的指纹还可以进行后续的DNA提取及检测,这是传统的指纹显现粉末所不能及的。本研究为指纹物证和生物物证这两大物证的同时利用提供了有益参考。

Synthesis of LaPO4∶Ce,Tb Fluorescent Nanopowders and Their Applications in Nondestructive Development of Latent Fingerprints

LaPO4∶Ce,Tb fluorescent nanopowders with high quality were synthesized via a hydrothermal method.The size, phase,and fluorescent property of as-prepared fluorescent nanopowders were then characterized by transmission electron micros-copy (TEM),powder X-ray diffraction (XRD)measurements,and fluorescence spectroscopy (FS).The fluorescent nanopow-ders were well-dispersed and rod-like in shape,with an average diameter of about 20 nm and an average length of about 700 nm. The fluorescent nanopowders were of pure monoclinic LaPO4 structure.They could emit strong green fluorescence under the 254 nm ultraviolet excitation.The LaPO4∶Ce,Tb fluorescent nanopowders were finally used as novel fluorescent labels for the non-destructive development of latent fingerprints on various smooth substrates,and the developing contrast,sensitivity,selectivity, as well as the background interference were also discussed in detail.The experimental results showed that the latent fingerprints labeled by LaPO4∶Ce,Tb fluorescent nanopowders could give strong green emissions under 254 nm ultraviolet lights,and thus well-defined friction ridges with sharp edges and some detailed features could be clearly observed,with high contrast,high sensi-tivity,high selectivity,and low background interference.It was shown that our development procedure was facile,effective and well applicable with outstanding performance. More importantly,the extraction and detection of DNA in fingerprint residues could also be achieved after fingerprint development,which was almost impossible to achieve by using the traditional used devel-oping powders including metal powder,metallic powder,and fluorescent powder.Therefore,our work provides beneficial refer-ences for the full utilization of both fingerprints and DNA evidences.