Post-blast detection of traces of explosives by means of Fourier transform infrared spectroscopy

Samples obtained from debris after explosions of about 30 g of energetic materials were analyzed by means of Fourier transform infrared (FTIR) spectroscopy using both, Globar and synchrotron infrared radiation at the ISMI beamline of the Singapore synchrotron light source (SSLS). Low- and high-strength-of-explosion blasts were performed during each test run with the same explosive material. From the spectroscopic measurements, traces of unreacted explosives were found on more than 200 different materials that served as sample catchers in the explosions.The integrality of the experiments done confirmed that FTIR spectroscopy is a sufficiently sensitive method to detect traces of explosives in post-blast residues even of high-strength explosions. The method requires only a minimal amount of sample and enables accurate and very fast identification of the presence of explosive material. Finally, the synchrotron radiation infrared source provided one order of magnitude higher sensitivity compared to the conventional Globar source.     

Use of synchrotron-radiation-based FTIR imaging for characterizing changes in cell contents

FTIR imaging of individual cells is still limited by the low signal-to-noise ratio obtained from analysis of such weakly absorbing organic matter when using a Globar IR source. In this study, we used FTIR imaging with a synchrotron radiation source and a focal plane array detector to determine changes in the cellular contents of cryofixed cells after culture for 48 h on Si(3)N(4) substrate. Several spectral differences were observed for cells deprived of glucose compared with control cells: a lower amide I-to-amide II ratio (P < 0.01); a different secondary structure profile of proteins (obtained from amide I spectral region curve fitting), with a significant increase in non-ordered structure components (P < 0.01); and a higher ν(C = C-H)/ν(as)(CH(3)) absorption ratio (P < 0.01), suggesting increased unsaturation of fatty acyl chains. Therefore, our study has shown that FTIR imaging with a synchrotron radiation source enables determination of several spectral changes of individual cells between two experimental conditions, which thus opens the way to cell biology studies with this vibrational spectroscopy technique.     

High-resolution microspectroscopy and sub-nanosecond time-resolved spectroscopy with the synchrotron infrared source

Infrared produced as synchrotron radiation has useful qualities for a number of infrared measurement methods. The most important is the high source brightness, which allows infrared microspectroscopy to be performed on sample regions having a size equal to the wavelength of light (a few microns). The source is also pulsed, enabling time-resolved spectroscopy to be performed without the need for a high-speed infrared detector. This paper reviews the qualities of infrared synchrotron radiation, and shows performance capabilities for microspectroscopy and sub-nanosecond time-resolved spectroscopy. Results from the National Synchrotron Light Source infrared beamlines are presented or reviewed.     

Synchrotron radiation FTIR imaging in minutes: a first step towards real-time cell imaging

FTIR microscopy with a focal plane array (FPA) of detectors enables routine chemical imaging on individual cells in only a few minutes. The brilliance of synchrotron radiation (SR) IR sources may enhance the signal obtained from such small biosamples containing small amounts of organic matter. We investigated individual cells obtained from a cell culture specifically developed for transmission FTIR imaging using either a Globar or an SR source coupled to the same instrumentation. SR-IR source focussing was optimized to control the energy distribution on the FPA of detectors. Here we show that accessing the IR absorption distribution from all the organic contents of cells at 1 × 1 μm pixel resolution was possible only with high circulating current (≥1.2 A) illuminating a limited number of the FPA’s detectors to increase the signal-to-noise ratio of IR images. Finally, a high-current SR ring is mandatory for collecting FTIR images of biosamples with a high contrast in minutes.     

Micromachining of crosslinked PTFE by direct photo-etching using synchrotron radiation

Micromachining of crosslinked PTFE (polytetrafluoroethylene) using synchrotron radiation direct photo-etching method has been demonstrated. High aspect-ratio microfabrication was carried out. The etching rate of crosslinked PTFE was higher than that of non-crosslinked PTFE. Through the etching rate measurements of various samples, it was found that synchrotron radiation etching rate of crosslinked PTFE only depends on the degree of crosslinking, neither molecular weight nor crystallinity. The effect of molecular motion on etching process was discussed from temperature dependence data on etching rate. Furthermore, the surface region of synchrotron radiation irradiated sample was investigated by Fourier transform infrared spectroscopy and the experimental result showed that the modification induced by synchrotron radiation proceeded before desorption.     

Double pulse laser-induced breakdown spectroscopy of explosives: Initial study towards improved discrimination

Detecting trace explosive residues at standoff distances in real-time is a difficult problem. One method ideally suited for real-time standoff detection is laser-induced breakdown spectroscopy (LIBS). However, atmospheric oxygen and nitrogen contributes to the LIBS signal from the oxygen- and nitrogen-containing explosive compounds, complicating the discrimination of explosives from other organic materials. While bathing the sample in an inert gas will remove atmospheric oxygen and nitrogen interference, it cannot practically be applied for standoff LIBS. Alternatively, we have investigated the potential of double pulse LIBS to improve the discrimination of explosives by diminishing the contribution of atmospheric oxygen and nitrogen to the LIBS signal. These initial studies compare the close-contact (< 1 m) LIBS spectra of explosives using single pulse LIBS in argon with double pulse LIBS in atmosphere. We have demonstrated improved discrimination of an explosive and an organic interferent using double pulse LIBS to reduce the air entrained in the analytical plasma.     

Investigation of biodeteriorated historical textiles by conventional and synchrotron radiation FTIR spectroscopy

We have examined specimens of historical biodeteriorated cellulose textiles using synchrotron radiation and conventional source FTIR spectroscopy. The main aim of our research was to investigate structural changes caused by ageing and biodeterioration in different types of cellulose fibres. We compared the results, obtained with both methods regarding spectral quality and information obtained with each method. Additionally, we obtained mapping images of the cross sections of the investigated specimens using synchrotron FTIR in order to analyze structural changes in cross sections, caused due to biodeterioration.     

鞋底材料的傅立叶变换红外光谱类型分析

利用傅立叶变换红外光谱技术对收集的29种皮鞋类黑色鞋底样品进行了测定分析,其中24种样品来自不同品牌或型号,5种样品来自同一品牌同一厂家同一批次.从红外光谱图中可以看出,依据红外光谱图中特征峰的峰数、峰位、峰形可将29个鞋底样品分为3大类.同一大类的部分鞋底样品有着相似的红外光谱特征,但在相对峰高比和指纹区中一些弱吸收峰上仍然存在明显差异.同一品牌同一厂家同一批次的鞋底样品红外光谱特征基本一致.这表明傅立叶变换红外光谱法是鉴别鞋底材料的有效方法,可以为案件现场遗留的各种鞋底材料残渣及其擦痕提供种属鉴别及比对分析.     

<Emphasis Type="Italic">In Situ</Emphasis> Synchrotron Radiation Techniques: Watching Deformation-induced Structural Evolutions of Polymers

Synchrotron radiation (SR) provides highly brilliant light with tunable wavelength from hard X-ray to far infrared, on which scattering, spectroscopy and imaging techniques with high time and spatial resolutions have been developed for in situ study on biological system and materials like polymer. With examples on flow-induced crystallization of polymer, deformation of nanoparticle filler network in rubber composite and necking propagation in tensile stretch, current work attempts to demonstrate the advantages of in situ synchrotron radiation X-ray scattering, X-ray nano-CT and infrared imaging in the study of deformation-induced multi-scale structural evolutions of polymers. With time resolution up to sub-ms, synchrotron radiation is expected to play a great role in understanding non-equilibrium polymer physics under processing and service conditions, while high-throughput characterization platform based on synchrotron radiation opens the possibility to establish polymer Materials Genome database in processing parameter space within reasonable time, which can serve as the roadmap for industrial polymer processing and accelerate material innovation.     

Explosives detection with electron‐rich polymers

The application of polymeric films as alarms for explosive materials is a critical issue these days as mandated by homeland security requirements. Amongst the multiple advantageous points of applying polymer films in this area is the fact that they are cheap material, so they can be applied on a broad scale for low cost. The basic idea of the current work is based on the fact that common explosives are electron deficient because of the existence of the nitro‐groups in their chemical structures, and this causes their high affinities towards electron rich materials to form charge‐transfer complex. Our endeavor is to trace any charge‐transfer complex formation, which would definitely cause a recognizable change in their physical properties. These changes in the polymers' physical properties could be utilized as alerts for the existence of explosive materials, especially if such changes could be incorporated into sophisticated electronic circuits that would give strong for traces of explosives. Copyright © 2013 John Wiley & Sons, Ltd.     

In Situ Synchrotron Radiation Techniques: Watching Deformation-induced Structural Evolutions of Polymers

Synchrotron radiation(SR) provides highly brilliant light with tunable wavelength from hard X-ray to far infrared, on which scattering, spectroscopy and imaging techniques with high time and spatial resolutions have been developed for in situ study on biological system and materials like polymer. With examples on flow-induced crystallization of polymer, deformation of nanoparticle filler network in rubber composite and necking propagation in tensile stretch, current work attempts to demonstrate the advantages of in situ synchrotron radiation X-ray scattering, X-ray nano-CT and infrared imaging in the study of deformation-induced multi-scale structural evolutions of polymers. With time resolution up to sub-ms, synchrotron radiation is expected to play a great role in understanding non-equilibrium polymer physics under processing and service conditions, while high-throughput characterization platform based on synchrotron radiation opens the possibility to establish polymer Materials Genome database in processing parameter space within reasonable time, which can serve as the roadmap for industrial polymer processing and accelerate material innovation.     

Laser-based standoff detection of explosives: a critical review

A review of standoff detection technologies for explosives has been made. The review is focused on trace detection methods (methods aiming to detect traces from handling explosives or the vapours surrounding an explosive charge due to the vapour pressure of the explosive) rather than bulk detection methods (methods aiming to detect the bulk explosive charge). The requirements for standoff detection technologies are discussed. The technologies discussed are mostly laser-based trace detection technologies, such as laser-induced-breakdown spectroscopy, Raman spectroscopy, laser-induced-fluorescence spectroscopy and IR spectroscopy but the bulk detection technologies millimetre wave imaging and terahertz spectroscopy are also discussed as a complement to the laser-based methods. The review includes novel techniques, not yet tested in realistic environments, more mature technologies which have been tested outdoors in realistic environments as well as the most mature millimetre wave imaging technique. Figure Standoff detection and identification is one of the most wanted capabilities     

The very far-infrared spectra of energetic materials and possible confusion materials using terahertz pulsed spectroscopy

We have measured the terahertz absorption spectra of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), pentaerythritol tetranitrate (PETN), 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), 2,4,6-trinitrotoluene (TNT), the plastic explosives Semtex H, SX2, and Metabel, and a number of confusion materials using terahertz pulsed transmission spectroscopy. Spectral fingerprints were obtained from 3 to 133 cm⁻¹. The spectra of the plastic explosives are dominated by the spectral signatures of their explosive components due to low frequency vibrations and crystalline phonon modes. Importantly, the terahertz spectra of the confusion materials show no resemblance to the explosives spectra. The refractive indices obtained for the plastic explosives and confusion materials allowed us to derive reflectance spectra, which appear distinct and so suggest that terahertz reflection spectroscopy is a suitable tool for the detection of concealed explosives in security applications.     

常见炸药的稳定同位素比值分析方法研究进展

炸药的深度比对与溯源对于爆炸案事件的侦破具有重大意义,以不同地域来源的原料或不同生产工艺生产的炸药,其组成元素的稳定同位素比值具有差异,因而稳定同位素比值可作为炸药深度比对与溯源的重要指标。稳定同位素比值质谱法(IRMS)作为一种高精度的稳定同位素比值测量手段,已逐渐发展成熟,与元素分析仪、气相色谱仪、液相色谱仪等仪器联用,在食品安全、环境保护、法庭科学等领域应用广泛。IRMS在炸药比对与溯源上亦发挥了重要作用,自1975年IRMS被应用于区分不同国家生产的三硝基甲苯(TNT)以来,IRMS已成功用于多种炸药的分析。但目前尚未见有文献系统地总结常见炸药的稳定同位素比值分析研究进展。该文介绍了稳定同位素比值分析的相关原理、仪器组成及特点,分别总结了硝酸铵、黑火药、TNT、太恩、黑索金等常见炸药的稳定同位素比值分析方法,汇总了文献报道的不同国家生产的硝酸铵、黑火药、TNT等炸药的稳定同位素比值。文章就不同炸药的稳定同位素比值差异、炸药生产、存储过程中相关因素对同位素比值的影响,爆炸前后稳定同位素比值的变化情况等内容进行了分析。本文还指出了目前炸药的稳定同位素比值分析研究中存在的问题,对可能的解决办法进行了讨论,对未来的发展方向提出了建议。     

Atomic level characterization by synchrotron radiation for the design of high performance catalysts

SPring-8 is the largest third-generation synchrotron radiation facility in the world. Synchrotron radiation is the most powerful light source currently available, especially in the EUV and X-ray regions, and in the research area of catalysis synchrotron radiation offers a very useful analysis method, i.e. XAFS. This spectroscopic investigative technique enables the determination of the chemical states and local structure of the atoms in the specific elements of a sample. Here, we introduce the SPring-8 facility and report how synchrotron radiation XAFS spectroscopy is utilized for the characterization and analysis of catalysts.     

Infrared spectromicroscopy of biochemistry in functional single cells

Over the years Fourier-Transform Infrared (FTIR) spectroscopy has been widely employed in the structural and functional characterization of biomolecules. The introduction of infrared (IR) microscopes and of synchrotron light sources has created expectations that FTIR could become a generally viable technique to study both structure and reactivity in vivo, inside single cells, by performing measurements that up to a few years ago were the preserve of in vitro experiments on purified macromolecules. In this review we present the state-of-the-art in the application of FTIR spectromicroscopy as a technique for the study of structure and dynamics in single cells, we discuss the performance requirements for this application and review developments in sample handling methods.     

同步辐射红外光谱技术在生物医用领域的应用

同步辐射作为一种新型红外光源,具有光谱宽、亮度高、分辨率高的特性,在生命科学领域具有广泛的应用。随着同步红外显微镜成像技术的不断发展,同步辐射红外光谱技术可以在原位探测亚细胞级别的生物化学变化,并保留细胞的生命特征。通过对蛋白质、核酸、磷脂等成分的定性和定量分析,可以了解骨细胞、神经细胞的病变,癌变细胞的活动情况以及植物细胞的营养状况等。同时,同步辐射红外光谱技术的应用范围正在不断扩展,其在药物释放的检测和生物化学过程的监控等方面也具有相当的应用前景。此外,在生物分子的分子间振动能级所处的远红外区,同步辐射红外光谱相比于常规红外光谱具有较高的信噪比。     

Applications of synchrotron radiation in forensic trace evidence analysis

Synchrotron radiation sources have proven to be highly beneficial in many fields of research for the characterization of materials. However, only a very limited proportion of studies have been conducted by the forensic science community. This is an area in which the analytical benefits provided by synchrotron sources could prove to be very important. This review summarises the applications found for synchrotron radiation in a forensic trace evidence context as well as other areas of research that strive for similar analytical scrutiny and/or are applied to similar sample materials. The benefits of synchrotron radiation are discussed in relation to common infrared, X-ray fluorescence, tomographic and briefly, X-ray diffraction and scattering techniques. In addition, X-ray absorption fine structure analysis (incorporating XANES and EXAFS) is highlighted as an area in which significant contributions into the characterization of materials can be obtained. The implications of increased spatial resolution on microheterogeneity are also considered and discussed.     

Detection of trace materials with Fourier transform infrared spectroscopy using a multi-channel detector

FTIR spectroscopy is one of the most powerful methods for material characterization. However, the sensitivity of this analytical tool is often very limited especially for materials with weak infrared absorption or when spectral bands of the targeted trace material overlap with the spectral bands of major components. Fortunately, for heterogeneous samples, there is an opportunity to improve the sensitivity of detection by using an imaging approach. This paper explores the opportunity of enhancing the sensitivity of FTIR spectroscopy to detect trace amounts of materials using the FTIR imaging approach based on a focal plane array (FPA) detector. Model sample tablets of ibuprofen in hydroxypropyl methylcellulose (HPMC) have been used to exemplify the detection limits of FTIR spectroscopy using: (a) a conventional mercury cadmium telluride (MCT) detector and (b) a FPA detector. The sensitivity level was compared and it has been found that for this particular set of samples, the lowest concentration of ibuprofen in HPMC that can be detected using attenuated total reflection (ATR) measuring mode with the single element MCT detector was 0.35 wt% while using the FPA detector, the presence of drug has been detected in a sample that contains as little as 0.075 wt% of drug. The application of using this enhanced sensitivity offered by the multi-channel detector to probe trace amounts of drug particles left on the surface of a finger after handling a small amount of the drug has also been demonstrated. These results have broad implications for forensic, biomedical and pharmaceutical research.     

Rapid on-site detection of explosives on surfaces by ambient pressure laser desorption and direct inlet single photon ionization or chemical ionization mass spectrometry

Considering current security issues, powerful tools for detection of security-relevant substances such as traces of explosives and drugs/drug precursors related to clandestine laboratories are required. Especially in the field of detection of explosives and improvised explosive devices, several relevant compounds exhibit a very low vapor pressure. Ambient pressure laser desorption is proposed to make these substances available in the gas phase for the detection by adapted mass spectrometers or in the future with ion-mobility spectrometry as well. In contrast to the state-of-the-art thermal desorption approach, by which the sample surface is probed for explosive traces by a wipe pad being transferred to a thermal desorber unit, by the ambient pressure laser desorption approach presented here, the sample is directly shockwave ablated from the surface. The laser-dispersed molecules are sampled by a heated sniffing capillary located in the vicinity of the ablation spot into the mass analyzer. This approach has the advantage that the target molecules are dispersed more gently than in a thermal desorber unit where the analyte molecules may be decomposed by the thermal intake. In the technical realization, the sampling capillary as well as the laser desorption optics are integrated in the tip of an endoscopic probe or a handheld sampling module. Laboratory as well as field test scenarios were performed, partially in cooperation with the Federal Criminal Police Office (Bundeskriminalamt, BKA, Wiesbaden, Germany), in order to demonstrate the applicability for various explosives, drugs, and drug precursors. In this work, we concentrate on the detection of explosives. A wide range of samples and matrices have been investigated successfully.