显微红外光谱仪与显微拉曼光谱仪对纺用无色单根纤维的检测

目的研究常见纺用单根无色纤维的有效鉴别方法。方法使用显微红外光谱仪、显微激光拉曼光谱仪研究7大类纺用单根无色纤维的分子光谱。结果显微红外光谱仪、显微激光拉曼光谱仪能有效区分包括棉、粘胶、羊毛、丝、聚酰胺、聚丙烯腈和聚酯在内的7种纤维,是检测单根纤维的有效手段。785nm激发光源是显微激光拉曼光谱仪研究这7类纤维的最佳波长。但由于纺用纤维生产过程的标准化,仅依据红外或者拉曼的峰位置区分同种类、不同产地纤维的效果一般。结论显微红外光谱仪、显微激光拉曼光谱仪是鉴别常见纺用单根无色纤维的有效方法。     

显微激光拉曼光谱鉴别直接染料及其染色纤维

目的 研究显微激光拉曼光谱对直接染料及其染色纤维的鉴别.方法 使用显微激光拉曼光谱仪分别检验了9种直接蓝染料、6种直接黑染料和6种直接红染料及其染色的棉、苎麻和粘胶纤维.结果 当使用显微激光拉曼光谱仪检测直接染料时,514nm激光器的区分能力较强,且光谱基本不受荧光干扰;633nm和785nm激光器的区分能力相似,但较514nm激光器略弱,且光谱更易受到荧光干扰.当使用显微激光拉曼光谱仪检测染色纤维时,若染料本身拉曼光谱信号较强时,其染色纤维的拉曼光谱与染料基本一致;当染料本身拉曼光谱信号较弱且受荧光干扰时,其染色纤维的拉曼光谱受到更大荧光干扰;相同染料染色的不同纤维的拉曼光谱一致.结论 显微激光拉曼光谱是无损检验染料及其染色纤维的有效手段,染色纤维的拉曼光谱基本反映的是染料的拉曼信号.     

激光显微共聚焦拉曼光谱仪对红色墨迹的研究

目的利用激光显微共聚焦拉曼光谱仪对文书中常见的红色墨迹材料进行表征,研究该方法对红色墨迹材料的区分能力。方法在785nm激发波长,50倍物镜条件下,对49种红色印文,以及9种彩色喷墨打印和13种彩色激光打印的红色墨迹材料进行拉曼光谱表征。结果通过对71种墨迹样品的谱图进行分析,可以发现,红色印文墨迹、喷墨打印红色墨迹及激光打印红色墨迹的拉曼光谱间均存在差异,同时,拉曼光谱可将这三种墨迹材料分别进一步区分。结论显微共聚焦激光拉曼光谱可对红色墨迹材料进行有效表征和区分。这一方法可对红色印文墨迹进行识别,并且可实现对伪造印文文件的鉴别。     

线聚焦显微激光拉曼光谱技术区分激光打印墨粉

目的利用Renishaw InVia激光显微拉曼光谱仪对打印墨粉进行区分。方法用785nm激发波长,采取线聚焦模式,50倍物镜条件下,测定了惠普等8个品牌25种硒鼓型号的30份激光打印机打印墨迹样品的拉曼光谱。结果 30种样品墨迹的谱图进行了分析,根据拉曼的异同,可将30种样品分为5大类。结论线聚焦显微激光拉曼光谱可用于区分不同种类激光打印墨粉。     

显微激光拉曼光谱技术区分喷墨打印墨迹研究

目的运用激光显微共聚焦拉曼光谱仪对打印墨水的墨迹样品进行检验。方法采用514nm激发波长,测得EPSON、HP、CANON等3个品牌21种型号墨迹样品的拉曼光谱。结果根据拉曼峰位的异同,可将21种型号墨迹样品分为8大类。结论该方法可以快速区分常见不同种类打印墨水墨迹,为印刷文件的检验鉴定提供方法参考。     

显微共焦拉曼光谱技术区分喷墨打印机打印的彩色图文墨迹

目的建立显微共焦拉曼光谱法区分喷墨打印机打印的彩色图文墨迹的方法。方法利用显微共焦拉曼光谱技术所具有微量、微区、原位分析及非破坏性等特点,对24种常见彩色墨水墨迹分别进行检验。结果品红色墨点墨迹成分归类区分效果最好,其次是黄色墨点,最后是蓝色墨点。结论采用显微共焦拉曼光谱技术对彩色打印墨迹进行不同颜色单点分析可大大提高喷墨打印机厂家型号的识别率,是一种有效的检测手段。     

拉曼光谱法鉴别常见毒品

目的建立一种识别毒品与其它常见白色物质的方法。方法使用激光显微拉曼光谱法对7种毒品和5种白色粉末进行了分析。结果7种常见毒品均有丰富的拉曼位移峰,可以通过其位移峰峰位的不同区分不同成分的毒品。另外,通过拉曼位移峰的峰位,还可以将7种常见毒品与5种常见白色粉末区分开来。结论拉曼光谱法适用于快速准确地识别毒品。     

显微共焦激光拉曼光谱仪分析激光打印黑色墨粉字迹

激光打印机是常用办公设备,案件中经常会涉及到激光打印文件的检验,运用显微共焦激光拉曼光谱仪检验激光打印黑色墨粉字迹是一种快速、无损、灵敏度高的检验方法,可以对墨粉成分进行定性分析,在司法实践中,此种方法对激光打印黑色墨粉具有较好的检验效果,应用前景广阔。     

拉曼光谱法鉴别常见炸药

目的建立一种识别炸药的方法。方法使用激光显微拉曼光谱法对17种常见炸药粉末进行了分析。结果17种常见炸药均有丰富的拉曼位移峰,可以通过其位移峰峰位的不同区分不同成分的炸药。结论拉曼光谱法适用于快速准确地识别炸药。     

黑色墨迹的拉曼光谱分析

目的对常见的黑色墨迹进行初步筛选,为墨迹的进一步检验提供依据。方法依据黑色墨迹的同色异谱特征,利用显微共焦激光拉曼光谱仪对19种黑色墨迹进行分析检验。结果根据不同墨迹的拉曼谱图,19种黑色墨迹可以分为3大类,即:未检出拉曼峰的墨迹,只检出碳物质的墨迹,以及主体色料为染料的墨迹。结论拉曼光谱可用于区分不同种类黑色墨迹,从而为选择合适的方法对黑色墨迹进一步进行检验奠定基础。     

Application of Infrared and Raman Spectroscopy in Paint Trace Examination

Raman spectroscopy has proved to be a promising technique in forensic examinations, where optical microscopy, micro‐infrared spectroscopy, and microspectrophotometry in the visible and UV range are used for identification and differentiation between paint traces. Often no organic pigments are detected using Fourier transform infrared spectroscopy, because their content in a trace is usually undetectable. Application of a micro‐Raman spectrometer equipped with several excitation lasers helps forensic experts in paint analysis enabling identification of main pigments. Three cases concerning comparative examination of car paint are discussed in detail. The comparison of Raman spectra of paint chips found on clothing of a victim or smears found on body of a damaged car to these of paint chips originated from the suspected car enabled us to identify the car involved in the accident. When no comparative material is available, the method can be useful in establishing the color and make of the car.     

The Analysis of Colored Acrylic,Cotton, and Wool Textile Fibers Using Micro‐Raman Spectroscopy. Part 2: Comparison with the Traditional Methods of Fiber Examination

In the second part of this survey, the ability of micro‐Raman spectroscopy to discriminate 180 fiber samples of blue, black, and red cottons, wools, and acrylics was compared to that gathered with the traditional methods for the examination of textile fibers in a forensic context (including light microscopy methods, UV‐vis microspectrophotometry and thin‐layer chromatography). This study shows that the Raman technique plays a complementary and useful role to obtain further discriminations after the application of light microscopy methods and UV‐vis microspectrophotometry and assure the nondestructive nature of the analytical sequence. These additional discriminations were observed despite the lower discriminating powers of Raman data considered individually, compared to those of light microscopy and UV‐vis MSP. This study also confirms that an instrument equipped with several laser lines is necessary for an efficient use as applied to the examination of textile fibers in a forensic setting.     

激光喇曼光谱在物证分析中的应用

在侦察工作中,要想及时地揭露犯罪和有效地证实犯罪,就必须准确地鉴别微量物证。激光喇曼技术是研究分子结构的重要手段之一,在分析和鉴定微量的纤维、橡胶、塑料、涂料、爆炸物、油墨和墨水等物证时,有很大的优越性。     

A More Efficient Method for Synthetic Textile Fiber Analysis Using Polarized Light Microscopy

The efficiency of conventional polarized light microscopy (PLM) methods for analyzing synthetic fiber evidence analyses is improved. Historically, using PLM for fiber identification relied on measuring refractive index. This prior PLM technology is reliable, but it is not efficient. Most fibers are optically anisotropic, having two principal refractive index values, N_(High) and N_(Low). When the fiber is mounted in intermediate refractive index medium, efficiency is improved by observing the change in contrast while the polarized light’s vector is rotated relative to the fiber’s axis. Minimum contrast occurs when the refractive indices of the mounting medium and fiber are equal. This angle of equality is determined by orienting the fiber’s highest refractive index parallel to the polarized light’s electric field vector, rotating the fiber or polarizing element, observing minimum contrast and measuring the angle of equality. This method is rapid, reduces remounting fibers in different mounting media and provides a quantitative measure for fiber comparisons.     

Identification of Different Forms of Cocaine and Substances Used in Adulteration Using Near‐infrared Raman Spectroscopy and Infrared Absorption Spectroscopy

Identification of cocaine and subsequent quantification immediately after seizure are problems for the police in developing countries such as Brazil. This work proposes a comparison between the Raman and FT‐IR techniques as methods to identify cocaine, the adulterants used to increase volume, and possible degradation products in samples seized by the police. Near‐infrared Raman spectra (785 nm excitation, 10 sec exposure time) and FT‐IR‐ATR spectra were obtained from different samples of street cocaine and some substances commonly used as adulterants. Freebase powder, hydrochloride powder, and crack rock can be distinguished by both Raman and FT‐IR spectroscopies, revealing differences in their chemical structure. Most of the samples showed characteristic peaks of degradation products such as benzoylecgonine and benzoic acid, and some presented evidence of adulteration with aluminum sulfate and sodium carbonate. Raman spectroscopy is better than FT‐IR for identifying benzoic acid and inorganic adulterants in cocaine.     

Source Determination of Red Gel Pen Inks using Raman Spectroscopy and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy combined with Pearson's Product Moment Correlation Coefficients and Principal Component Analysis

The potential combination of two nondestructive techniques, that is, Raman spectroscopy (RS) and attenuated total reflectance–fourier transform infrared (ATR‐FTIR) spectroscopy with Pearson's product moment correlation (PPMC) coefficient (r) and principal component analysis (PCA) to determine the actual source of red gel pen ink used to write a simulated threatening note, was examined. Eighteen (18) red gel pens purchased from Japan and Malaysia from November to December 2014 where one of the pens was used to write a simulated threatening note were analyzed using RS and ATR‐FTIR spectroscopy, respectively. The spectra of all the red gel pen inks including the ink deposited on the simulated threatening note gathered from the RS and ATR‐FTIR analyses were subjected to PPMC coefficient (r) calculation and principal component analysis (PCA). The coefficients r = 0.9985 and r = 0.9912 for pairwise combination of RS and ATR‐FTIR spectra respectively and similarities in terms of PC1 and PC2 scores of one of the inks to the ink deposited on the simulated threatening note substantiated the feasibility of combining RS and ATR‐FTIR spectroscopy with PPMC coefficient (r) and PCA for successful source determination of red gel pen inks. The development of pigment spectral library had allowed the ink deposited on the threatening note to be identified as XSL Poppy Red (CI Pigment Red 112).     

In situ Study on the Diffusion Kinetics of Seal Ink by Microinfrared Spectroscopy

In document examination, it is of great importance to determine the composition of seal ink with different imprint times, and spectroscopic methods are widely used today. In this research, the diffusion of seal inks from three different brands on the same type of paper is monitored in situ by microinfrared spectroscopy and microinfrared imaging technology. The area of the absorption peak at 1743 cm^?1 gradually decreases with increasing diffusion time. The diffusion kinetics of seal ink on paper are also studied by analyzing the infrared spectra of seal inks at the same measuring point with different diffusion times. The research provides a basic study in understanding the diffusion behavior of seal ink on paper over short time spans.     

The Effects of Environmental Exposure on the Optical,Physical, and Chemical Properties of Manufactured Fibers of Natural Origin

Manufactured fibers derived from natural origins include viscose rayon, azlon, and polylactic acid (PLA). A 2‐year study was conducted to document any changes these fibers undergo as a result of exposure to various environmental conditions. Fabric swatches representing each fiber type were exposed to freshwater, saltwater, heat, cold, ultraviolet light, or composter conditions. Fibers from the swatches were periodically analyzed using polarized light microscopy and Fourier transform infrared microspectroscopy. Fiber solubility and melting‐point behavior were measured every 6 months. Except for the complete degradation of viscose rayon in the composter, saltwater, and freshwater environs, no changes in the optical properties, infrared spectra, solubility, or melting points of the remaining fibers in any of the environments were observed. However, microscopic morphological changes were observed in fibers from two azlon swatches submerged in freshwater and saltwater, two PLA swatches exposed to ultraviolet light, and two viscose rayon swatches exposed to ultraviolet light.     

Real‐Time Detection of Concealed Chemical Hazards Under Ambient Light Conditions Using Raman Spectroscopy

Current concerns regarding terrorism and international crime highlight the need for new techniques for detecting unknown and hazardous substances. A novel Raman spectroscopy‐based technique, spatially offset Raman spectroscopy (SORS), was recently devised for noninvasively probing the contents of diffusely scattering and opaque containers. Here, we demonstrate a modified portable SORS sensor for detecting concealed substances in‐field under different background lighting conditions. Samples including explosive precursors, drugs, and an organophosphate insecticide (chemical warfare agent surrogate) were concealed inside diffusely scattering packaging including plastic, paper, and cloth. Measurements were carried out under incandescent and fluorescent light as well as under daylight to assess the suitability of the probe for different real‐life conditions. In each case, it was possible to identify the substances against their reference Raman spectra in less than 1 min. The developed sensor has potential for rapid detection of concealed hazardous substances in airports, mail distribution centers, and customs checkpoints.