拉曼光谱成像技术检验朱墨时序中书写笔种类对检验结果的影响研究

目的考察在运用拉曼光谱阵列面扫描检验朱墨时序的方法中书写笔油墨种类对检验结果的影响。方法根据拉曼谱图的不同对搜集的188种书写笔（包括22种黑色圆珠笔,62种蓝色圆珠笔,62种黑色签字笔,42种蓝色签字笔）进行扫描并分类,采用拉曼光谱阵列面扫描技术对书写笔与同一印泥和印油形成的朱墨时序样本进行检验。结果 188种书写笔被分为4大类23小类,4类书写笔与印泥或印油形成的朱墨时序样本都得到了较好的检验结果。结论在本实验条件下,书写笔油墨种类对拉曼光谱阵列面扫描检验朱墨时序的检验结果没有影响。     

显微激光拉曼光谱法鉴别黑色圆珠笔油墨的初步研究

利用显微激光拉曼光谱法对纸张上黑色圆珠笔油墨字迹进行检验,结果表明 ,对不同的黑色圆珠笔油墨可以有效鉴别。该方法快速、简便、不破坏样品。     

LAB图像处理模式区分黑色圆珠笔字迹的方法验证

目的考察验证LAB模式区分黑色圆珠笔字迹的方法,以及油墨浓淡对检验结果的影响。方法采用600dpi分辨率扫描样品并将图像保存成tiff格式,运用PhotoshopCS3图像处理软件中Lab模式进行处理。结果Lab模式无损区分黑色圆珠笔字迹的识别率达到61．67％,且油墨浓淡对实验结果影响不明显。结论此方法可用于黑色圆珠笔字迹的区分检验。     

表面增强拉曼光谱对黑色圆珠笔快速鉴别的检测研究

目的 建立圆珠笔油墨的表面增强拉曼光谱分析方法,实现更加有效的圆珠笔样品种类区分。方法 选用纳米银胶体作为增强试剂,在785、633、514 nm 3种激发光波长下,分析检测市场上55支黑色圆珠笔的表面增强拉曼光谱,并通过将各激发光波长下的数据相结合来综合分析种类区分信息。结果 根据表面增强拉曼光谱图可有效区分出不同品牌圆珠笔油墨之间的差异。与增强前的拉曼光谱相比,增强之后的谱峰信号更强,在进行种类区分时更具说服力。785、633、514 nm 3种激发光波长的谱图信息相结合可获取更多有效的区分信息。结论 该方法能够有效鉴别不同品牌同一颜色的圆珠笔油墨,为司法鉴定中油墨成分的快速鉴别提供新思路。     

拉曼光谱成像技术检验朱文时序时印文油墨种类对检验结果的影响

目的考察在运用拉曼光谱阵列面扫描检验朱文时序的方法中印文油墨种类对检验结果的影响。方法根据拉曼谱图的不同对搜集的21种印泥印油进行扫描并分类,采用拉曼光谱阵列面扫描技术对印泥印油与同一书写笔形成的朱文时序样本进行检验。结果 21种印泥印油被分为11类,21种印泥印油与蓝色签字笔形成的朱文时序样本都得到了良好的检验结果。结论印文油墨种类用拉曼光谱阵列面扫描检验朱文时序的检验结果没有影响。     

光谱成像检验同种同色涂抹掩盖字迹研究

目的建立一种无损、灵敏、直观的同种同色涂抹掩盖字迹的显现方法。方法依据涂抹掩盖字迹油墨物质的同色异谱特征,利用可见光滤波型多光谱成像检验系统进行检验。结果黑色圆珠笔、蓝色圆珠笔、黑色签字笔和蓝色签字笔相互涂抹掩盖形成的同种同色涂抹掩盖样本,利用可见光滤波型多光谱成像检验系统进行检验,显效率分别为90.5%、69.1%、49.5%、78.6%,显现效果良好。结论多光谱成像技术可以显现同种同色涂抹掩盖字迹,且具有良好的显现效果。     

鉴定笔画交叉时序的新方法

笔画交叉时序鉴定历来是刑事科学技术物证检验工作的难点之一。当前,鉴定可疑文件笔画交叉时序的方法通常有三种:(1)借助显微镜,发现一些表观特征;(2)利用打字机胶带提取技术来提取交叉处圆珠笔笔画;(3)通过测量交叉笔画与样本的色度差来判定书写顺序。由于交叉处有色料混合现象,传统的方法仍存在缺点和不足。台湾学者KUN-CHENG,M.SC发明了一种新方法:使用激光扫描同焦     

书写材料的无损检验系统研究

本研究运用显微分光光度仪、文件检验仪和傅立叶变换拉曼光谱仪三种方法,分别对在中国市场上收集的不同厂家、牌号、型号的35种黑墨水、20种蓝黑墨水、22种蓝墨水、49种黑色墨水笔、30种蓝色墨水笔、45种黑色圆珠笔、和50种蓝色圆珠笔等七组样品进行非破坏检验。结果表明:(1三种非破坏检验方法都能单独对七组样品进行不同程度的鉴别,区分率在50%—94.4%之间;(2)三种方法联用后对黑墨水、蓝黑墨水、蓝墨水、黑色墨水笔、蓝色墨水笔、黑色圆珠笔和蓝色圆珠笔的区分率可分别提高到93.4%、97.3%、99.1%97.2%、97.2%、95.6%和91.8%。通过三种非破坏检验方法的联用,证明它们之间有较强的互补性,最大限度地提高了检验效应,可建立系统的非破坏检验方法。     

用计算机图像扫描技术检验添加笔迹

１案例２００１年１月１０日，汉中市中级人民法院受理一起因改借条引发的民事纠纷上诉案。其手法是在原借条上“二”中间添加一横，变为“三”字，达到赖掉五万元债务的目的。２方法用计算机图象扫描仪对借条进行扫描，利用Photoshop图象处理软件进行特征强化处理（图１、２），可见该借条系同一书写工具圆珠笔书写，“三”字笔画间的连笔痕迹系圆珠笔油迹。图象检验可见：检材“三”字第一笔画，起笔整齐，行笔用力均匀，收笔转折连笔痕迹，见A处。其方向与第二笔画起笔未见对应关系；第二笔画，起笔重，行笔前重后轻，且有收笔拖痕，未…     

印文与书写字迹交叉笔画先后顺序的消色差显微检验法

印文与书写字迹交叉笔画先后顺序的检验,一直是我国文件检验领域中未能很好解决的课题。对印文与书写字迹交叉笔画先后顺序的检验,常规采用放大镜及普通立体显微镜观察,或采用化学反应法、溶剂溶解法进行检验,效果均不很理想。1978年黄金铎、陈志卿提出用断层镜检法检验印文与书写迹交叉笔画的先后     

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。     

Raman Microspectroscopic Mapping: A Tool for Identification of Fused Materials in Fire Debris

Examination of fire debris can provide information about the types of materials which were present at the time of the fire to give insights for fire scene reconstruction and understanding compartment fire dynamics. This paper demonstrates the ability of Raman spectroscopy for material identification postfire in complex situations, such as the production of fused masses during fire dropdown. A validated Raman spectral library is combined with Raman mapping in three fire case studies, to determine the individual materials in the fused masses formed. The case studies accessed material combinations of several common polymers. Raman mapping was carried out on a 10 μm × 10 μm square of the masses. Material identification using this technique ranged from a high of 85% match to a low of 40% match. This work demonstrated that complex masses found in the fire debris can be resolved into the individual material components for identification and spatial distribution.     

Application of Raman spectroscopy in forensic investigation of questioned documents involving stamp inks

Stamp pad inks from different manufacturers across India have been analyzed to investigate the feasibility of Raman scattering as a tool for forensic analysis of questioned documents involving stamp inks. Nine different stamping inks were analyzed by both Raman spectroscopic and HPTLC methods. The results demonstrate the effectiveness of these methods in classifying the investigated stamping inks based on their spectral pattern and HPTLC chromatogram. Raman scattering tool was able to determine the sequence of heterogeneous intersection strokes involving a blue stamp pad ink and other writing instruments, such as ballpoint pen ink (red and black), pencil and laser printer toner. However, this method was unable to resolve the exact sequencing for the intersection strokes involving investigated stamp ink and blue ballpoint ink or gel pen ink (all colors).     

Using Raman Spectroscopy to solve crime: inks, questioned documents and fraud

Raman microscopy is becoming a tool of major importance in forensic analysis, particularly of drugs and explosives. It is a non-invasive, non-destructive chemical probe allowing samples to be examined in their entirety without any preparation. This paper demonstrates the use of the technique as a general tool for inks analysis. Furthermore, it addresses two important issues that historically have been extremely difficult for the professional document examiner, namely, comparison of black ballpoint inks and the chronological sequencing of crossed ink lines. We show that Raman can successfully distinguish between a representative sample of commercially available black ballpoint inks. This data has been converted into a database for future reference. A method for chronological sequencing of crossed ink lines has been developed using confocal Raman microscopy. Case study work has shown the feasibility of this approach.     

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.     

The Discrimination of Colored Acrylic,Cotton, and Wool Textile Fibers Using Micro‐Raman Spectroscopy. Part 1: In situ Detection and Characterization of Dyes

Raman spectroscopy has been applied to characterize fiber dyes and determine the discriminating ability of the method. Black, blue, and red acrylic, cotton, and wool samples were analyzed. Four excitation sources were used to obtain complementary responses in the case of fluorescent samples. Fibers that did not provide informative spectra using a given laser were usually detected using another wavelength. For any colored acrylic, the 633‐nm laser did not provide Raman information. The 514‐nm laser provided the highest discrimination for blue and black cotton, but half of the blue cottons produced noninformative spectra. The 830‐nm laser exhibited the highest discrimination for red cotton. Both visible lasers provided the highest discrimination for black and blue wool, and NIR lasers produced remarkable separation for red and black wool. This study shows that the discriminating ability of Raman spectroscopy depends on the fiber type, color, and the laser wavelength.     

In Situ Identification of Semen Stains on Common Substrates via Raman Spectroscopy,,

The spectroscopic identification of body fluids in situ is a major objective in forensic science. This approach offers the confirmatory, nondestructive, rapid, and on‐scene identification of various body fluids. Although Raman spectroscopy has shown tremendous promise toward this goal in prior proof‐of‐concept experiments, a significant challenge which still remains is substrate interference. Here, an approach for detecting semen stains in situ on various substrates using Raman spectroscopy is explored. Simulated semen evidence was prepared on skin, glass, and various fabrics. Raman data were accumulated from stains without any pretreatment using a common confocal mapping spectrometer using 785 nm laser excitation. The results demonstrate that the spectroscopic interferences encountered by substrates can be reduced and eliminated using a combination of existing subtraction techniques and chemometric models. Heterogeneous substrates proved most challenging, however, automatic subtraction treatment, and location of fluid hotspots was able to elucidate a clear spectroscopic signature of semen in every instance.     

Forensic Identification of Blood in the Presence of Contaminations Using Raman Microspectroscopy Coupled with Advanced Statistics: Effect of Sand,Dust, and Soil

Body fluid traces recovered at crime scenes are among the most common and important types of forensic evidence. However, the ability to characterize a biological stain at a crime scene nondestructively has not yet been demonstrated. Here, we expand the Raman spectroscopic approach for the identification of dry traces of pure body fluids to address the problem of heterogeneous contamination, which can impair the performance of conventional methods. The concept of multidimensional Raman signatures was utilized for the identification of blood in dry traces contaminated with sand, dust, and soil. Multiple Raman spectra were acquired from the samples via automatic scanning, and the contribution of blood was evaluated through the fitting quality using spectroscopic signature components. The spatial mapping technique allowed for detection of “hot spots” dominated by blood contribution. The proposed method has great potential for blood identification in highly contaminated samples.     

Raman spectroscopy and the forensic analysis of black/grey and blue cotton fibres Part 1: investigation of the effects of varying laser wavelength

Raman spectroscopy was investigated to determine the optimal conditions, mainly laser wavelength/s, for the analysis of the commonly encountered black/grey and blue cotton fibres dyed with reactive dyes. In this first part, a single blue cotton fibre, its three dye components, and an undyed cotton fibre were analysed with five different laser wavelengths from two different Raman microprobe spectrometers. The quality of the spectra, fibre degradation and speed of acquisition were used to determine that, under the conditions used, the 785 and 830 nm lasers gave superior results. The 632.8 nm laser wavelengths provided good results with little acquisition time and no spectral degradation. Results indicate that, at least, the major dye component could be identified using Raman spectroscopy.     

The Capability of Raman Microspectroscopy to Differentiate Printing Inks

This study applies Raman microspectroscopy to differentiate the chemical components in printing inks of different brands, colors, and type using the 532 nm and 785 nm excitation wavelengths. Spectra were collected from 319 inks (78 inkjet, 76 toner, 79 offset, and 86 intaglio) representing various colors. Comparisons were performed to calculate discrimination capability percentages for each ink type. Overall, Raman microspectroscopy differentiates according to the following hierarchy: intaglio (96%), inkjet (92%), offset (90%), and toner (61%). The ability of Raman microspectroscopy to differentiate between same‐colored inks from different brands was dependent on the color and ink analyzed. Based on ink color, the discrimination capability ranged from 75 to 94% (inkjet), 0 to 86% (toner), and 0 to 77% (offset). Copper phthalocyanine was detected in cyan inks and various intaglio inks, while carbon black was identified in black inkjet, offset, and intaglio inks.