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[en] We developed a standoff Raman detection system for explosive molecules (EMs). Our system was composed of reflective telescope with 310 mm diameter lens, 532 nm pulse laser, and Intensified Charge-Coupled Device (ICCD) camera. In order to remove huge background noise coming from ambient light, laser pulses with nanosecond time width were fired to target sample and ICCD was gated to open only during the time when the scattered Raman signal from the sample arrived at ICCD camera. We performed standoff experiments with military EMs by putting the detector at 10, 20 and 30 m away from the source. The standoff results were compared with the confocal Raman results. Based on our standoff experiments, we were able to observe the peaks in the range of 1200 and 1600 cm-1, where vibrational modes of nitro groups were appeared. The wave numbers and shapes of these peaks may serve as good references in detecting and identifying various EMs
[en] Pottery is one of the main productions of the pre-Columbian cultures in the Mesoamerican area. Among the others, the estucado pottery represents a very particular type of ceramic, widespread in Maya territory but still never investigated systematically. The peculiarity of this ceramic lies in the unusual application of the color decoration and in the excellent conservation conditions. Seventeen ceramic fragments from El Salvador have been analysed by Raman spectroscopy, SEM/EDS and XRPD, both as fragments and in cross-sections, in order to investigate the manufacturing technique and to understand the good and unexpected conservation state. In both cases, the presence and the chemical nature of a thin white layer (engobe) between the ceramic bulk and the colored decorations seems to be determinant.
[en] This book deals with historical background of a laser and characteristic of analytical chemistry laser spectrometry using diode laser, analytical chemistry application of laser induce plasma spectral of the law ; biochemical materials analysis using strengthening Raman spectroscopy such as resonance Raman scattering and surface-enhanced Raman scattering spectroscopy, resonant ionization mass spectrometry technology using a laser, remote analysis technique using a laser and realtime ingredient analysis of submicrometer practice in air.
[en] Laser Raman spectroscopy is the powerful tool to investigate the molecular structure. However, the conventional analog signal often causes some problems in many experiments. For high resolution, small signals, or background (solvent) subtraction, the computer interface of the Raman spectroscopy is the essential one. Here the interface work done in our laboratory is described and some results through the softwares developed are displayed. (Author)
[en] Resonance Raman spectroscopy (RRS) potentially possesses many of the characteristics of an ideal verification technology. Some of these ideal traits are as follows: (1) very high selectivity and specificity to allow the deconvolution of a mixture of the chemicals of interest; (2) high sensitivity in order to measure a species at trace levels; (3) high reliability and long-term durability; (4) applicability to a wide range of chemicals (closely associated with item 1); (5) capability of sensing in a variety of environmental conditions; (6) independance of the physical state of the chemical; (7) capability of quantitative analysis; (8) capability for full signal development within seconds (response speed). In this paper, the authors assess the potential of RRS as a detection/identification technology for chemicals pertinent to nuclear materials production and processing. The basic principles behind this technique, both theoretical and experimental, are discussed, along with recent experimental results
[en] We fabricated small clusters of gold nanoparticles by using solid-supported aggregation of gold nanoparticles. The fabricated Au nanoclusters consisting mainly of dimers showed homogeneous characteristics in cluster size and SERS intensity. The SERS enhancement of 4-ABT molecules in an effective area within 2-nm gap appeared to be approximately 10. Detachment process by ultrasonication was successively carried out in order to use the nanoclusters as SERS probes. The possibility of these clusters as SERS probe was proved in terms of signal and cluster size. Single molecule-level sensitivity of surface-enhanced Raman scattering (SERS) was known approximately fifteen years ago. Ever since there have been many different applications benefiting from the ultra-high sensitivity such as single molecule detection, chemical sensing and bio-molecular probes. Especially, SERS has drawn much attention in bio-multiplexing probes owing to its unique optical characteristics claiming extremely narrow bandwidth, high sensitivity of light signals, and non-bleaching feature
[en] Full text: Plasmonic nanogap arrays have been fabricated by EUV lithography to explore their use as sensing substrates for surface enhanced Raman scattering (SERS). SERS is a well-known effect offering the unique molecule signature of Raman spectroscopy with strongly enhanced signal strengths for detection as low as nanomolar concentrations. Because the signal enhancement often has its origin from randomly distributed hotspots, SERS substrates to-date lack reproducibility over large areas. Our fabrication process of nanogap arrays is found to lead to superior reproducibility with standard deviations well below 5 %. This evolves from the high density of well controlled nanogaps leading to a deterministic origin of SERS. Optimization procedures of fabrication will be presented, and we will discuss the obtained correlation between experiments and simulation enabling an accurate prediction of the sensor performance. (author)
[en] Highlights: • DHI has been developed to assess distributional homogeneity in hyperspectral maps. • This criterion has been tested with simulated maps of different homogeneity. • A linear relationship is observed between homogeneity and DHI value. • DHI methodology has been applied on real samples. • A linear relationship is observed between DHI and content uniformity values. - Abstract: During galenic formulation development, homogeneity of distribution is a critical parameter to check since it may influence activity and safety of the drug. Raman hyperspectral imaging is a technique of choice for assessing the distributional homogeneity of compounds of interest. Indeed, the combination of both spectroscopic and spatial information provides a detailed knowledge of chemical composition and component distribution. Actually, most authors assess homogeneity using parameters of the histogram of intensities (e.g. mean, skewness and kurtosis). However, this approach does not take into account spatial information and loses the main advantage of imaging. To overcome this limitation, we propose a new criterion: Distributional Homogeneity Index (DHI). DHI has been tested on simulated maps and formulation development samples. The distribution maps of the samples were obtained without validated calibration model since different formulations were under investigation. The results obtained showed a linear relationship between content uniformity values and DHI values of distribution maps. Therefore, DHI methodology appears to be a suitable tool for the analysis of homogeneity of distribution maps even without calibration during formulation development
[en] Herein, we present Raman spectroscopy of chemically grafting aryl diazonium molecules onto single-layer graphene (SLG) and charge transport characteristics of the aryl alkane monolayers sandwiched between the SLG electrodes in an electrode/monolayers/electrode motif. Our spectroscopic characterization shows that the aryl component molecules were incorporated as an effective tunnel barrier into the SLG electrodes-based molecular junctions. The temperature-variable and length-dependent transport measurements clearly demonstrate that tunneling occurs through the SLG/monolayers/SLG junctions and the current density can be modulated with a correct decay coefficient (β) by the length of a molecular tunneling barrier.