论文总字数：21996字

摘 要

指纹具有人各不同的特性，所以指纹的显现成为现代刑侦过程中非常重要的一项工作。随着刑侦技术的发展，指纹的显现材料和显现方法也层出不穷，根据指纹遗留现场的环境、背景不同，不同的材料会产生不同的显现效果。基于上述问题，本文概述了传统指纹的提取方法，对指纹显现工作进行了总结，尤其是对磁性材料在指纹显现工作中的应用作了详细研究。

本文以二茂铁和三氯化铁为原料，制备了Fe₃O₄@C磁性纳米复合材料，通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、傅里叶红外光谱（FTIR）和X射线衍射法（XRD）对制备的Fe₃O₄@C复合纳米材料进行了形貌和结构表征。Fe₃O₄@C纳米复合材料呈球形，内核为Fe₃O₄，外部为包裹均匀的碳壳。由于Fe₃O₄@C具有很强的磁性，可以用作指纹的刷显粉末；同时，又由于它具有良好的亲水外壳，可形成稳定的乙醇分散液，用作指纹识别的喷显试剂。通过实验发现，最佳Fe₃O₄@C喷显浓度为0.6g·mL^-1。通过刷显和喷显实验，发现Fe₃O₄@C对光滑非渗透性客体上的潜在指纹具有良好的显现效果，并且经二次处理之后指纹纹线更加清晰，对渗透性客体表面遗留的指纹效果稍差，但是显现效果在同等情况下比普通磁性粉末有明显改善。

关键词：指纹显现 Fe₃O₄@C 磁性粉末 刷显法 喷显法

Application Research of Magnetic Nanocomposites in Fingerprint Appearance

ABSTRACT

Fingerprints have different characteristics, so the appearance of fingerprints has become a very important task in the modern criminal investigation process. With the development of technology, the fingerprinting materials and methods of visualization are also emerging. Different environment and background of the fingerprints left on the scene, the of the fingerprints will produce different effects. Based on the above problems, this paper comprehensively summarizes the traditional fingerprint extraction method and summarizes the fingerprint visualization work. The performance, synthesis and characterization of Fe₃O₄@C magnetic nanoparticles were investigated. And the effect is compared with traditional powder.

In this paper, Fe₃O₄@C magnetic nanocomposites were prepared by using ferrocene and ferric chloride as raw materials. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction method (XRD) were performed to characterize the morphology and structure of the prepared Fe₃O₄@C composite nanomaterials. The Fe₃O₄@C nanocomposite has a spherical shape with a core of Fe₃O₄ and a carbon shell with a uniform outer coating. Because Fe₃O₄@C has strong magnetic properties, it can be used as a fingerprinting powder. At the same time, because it has a good hydrophilic shell, it can form a stable ethanol dispersion and is used as a spray-reagent for fingerprint recognition. It was found after experiments that the optimal concentration of Fe₃O₄@C dispersion was 0.6 g mL^-1. Through the powder brushing and smear experiments, it was found that Fe₃O₄@C has a good visual effect on the potential fingerprint on the smooth non-permeable object, and the fingerprint line is clearer after the secondary treatment. The fingerprinting effect on the surface of the permeable object was also improved, compared with the ordinary magnetic powder under the same conditions.

Key words: fingerprint appearance; Fe₃O₄@C; brush display method; spray method

目录

摘要 I

ABSTRACT II

目录 IV

第一章 文献综述 1

1.1潜指纹 1

1.2指纹的化学组成 1

1.3传统指纹显现方式 2

1.3.1粉末显现法 2

1.3.2硝酸银显现法 3

1.3.3碘熏法 3

1.3.4 “502”胶熏显法 3

1.3.5 茚三酮显现法 4

1.3.6 DFO显现法 4

1.4纳米材料在指纹显现中的应用 5

1.5本论文研究的目的、内容和意义 5

第二章 实验部分 7

2.1 实验试剂 7

2.2实验仪器与设备 7

2.3 Fe₃O₄@C的制备及表征 7

2.4 指纹刷显实验 8

2.4.1样本的制备 8

2.4.2实验具体操作 8

2.5 指纹喷显实验 9

2.5.1不同浓度Fe₃O₄@C磁性纳米颗粒乙醇悬浮液的制备 9

2.5.2 样本的制备 9

2.5.3 实验具体操作 9

第三章 结果与讨论 9

3.1 Fe₃O₄@C磁性纳米颗粒的形貌与结构表征 9

3.1.1 Fe₃O₄@C的TEM和SEM表征 9

3.1.2 Fe₃O₄@C磁性纳米颗粒的傅里叶红外光谱分析 10

3.1.3 Fe₃O₄、Fe₃O₄@C的XRD衍射图谱分析 11

3.2 Fe₃O₄@C磁性纳米颗粒与传统磁性粉末对相同客体上不同陈旧度的 指纹刷显效果比较 12

3.3 Fe₃O₄@C磁性纳米颗粒与传统磁性粉末对不同客体上新鲜指纹刷显效果比较 14

3.4 不同浓度Fe₃O₄@C磁性纳米颗粒乙醇悬浮液显现效果的比较 15

3.5 Fe₃O₄@C磁性纳米颗粒乙醇分散液对不同客体上遗留指纹的喷显效果比较 17

第四章 结论与展望 19

4.1 实验结论 19

4.2展望 20

参考文献 22

致谢 25

第一章 文献综述

1.1潜指纹

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