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Atomic force microscopy (AFM), scanning electron microscopy (SEM), white light imaging measurements, and Raman microscopy were employed for the characterization of hexahydro-1,3,5-trinitro-1,3,5-s-triazine (RDX) nanoparticles deposited on glass substrate surfaces. The RDX nanoparticles were prepared by exposure of glass substrate surfaces to an aerosol jet containing RDX. The spectroscopic signature of RDX particles and the two known forms of the material, β and a RDX, are compared. Raman measurements reveal that RDX nanoparticles and β deposits have similar spectroscopic signatures between 750 and 1000 cm - 1 .

Deposits of β and α RDX on glass substrates have been examined with optical and Raman microscopy. The measurements reveal significant differences in the morphology and Raman spectra of β and α RDX. Structures that resemble an island, as well as scattered particles, are observed in white light images of β RDX. Well-defined crystals are observed in white light images of α RDX. The spectroscopic signature of these forms of RDX has marked differences in Raman frequencies and relative intensities. The transition from β to α RDX is driven by the amount of RDX deposited. There is a close agreement between measured and calculated vibrational frequencies for β and gas-phase RDX. A poor correlation is found between measured and predicted Raman intensities and depolarization ratios for β and gas-phase RDX, respectively. These differences lead us to conclude that the properties of β and gas phase RDX are markedly different, despite the similarities in the vibrational frequencies.

Explosives detection is a very important task for National Security. The formidable task includes development of new probes and methods for detection of concealed explosives which is of utmost priority to Homeland Security and other security enforcing federal agencies. Here we report on the detection of triacetone triperoxide (TATP) on metallic surfaces using a Fiber Optic Coupled FTIR method. FT-IR spectroscopy is well suited to be used outside the confinement of the sample compartment, provided the excitation source and the reflected light can be transported to the interferometer. Fiber optic cables that transmit in the Mid-IR range have made this possible by allowing the development of a range of spectroscopic probes for in situ analysis. In our study we used a specially designed sampling probe that operates at the grazing-angle to detect and to quantify μg/cm2 levels of explosives on stainless steel. Calibration curves were prepared using stainless steel plates, 3 inches wide x 6 inches long. The samples were deposited on the surface using a smearing method. To carry out the experiments, TATP was synthesized in the laboratory. For the calibration curves TATP was dissolved in dichloromethane. The standard solutions (20) μL were transferred on the plates resulting in surface mass concentrations of TATP that ranged from 8 to 150 μg/cm2. The data was analyzed using Chemometrics routines and Discriminant Analysis algorithms. In particular, multivariate Partial Least Squares (PLS) was used to determine the most significant peak for the analysis. In other experiments done with stainless steel plates coated with 150 μg/cm2 TATP, spectra were recorded every 27 seconds. For this concentration TATP sublimates to surface concentrations below detection in 800 s.

We report on the effect of trinitrotoluene (TNT) in the fluroescence emission of CdSe quantum dots covered with a ZnS core shell. Pulses of 100 femtoseconds are employed to excite the fluorescence of the dots off resonance. We found evidence for a strong quenching by TNT on the fluorescence emission of the quantum dots. The fluorescence emission of the QD experiences a blue or red shift that depends on the CdSe particle size and amount of TNT. The results are explained in terms of a charge transfer mechanism or a modification of the traps involved in electron relaxation in QD. The results show that QD are a promising tool for TNT sensing.

Non nitrogen containing, organic peroxides explosives Triacetone triperoxide and diacetone diperoxide have been prepared in the laboratory in order to study various aspects of their synthesis and their experimental and theoretical spectroscopic characteristics. By using different proportions of acetone/hydrogen peroxide (Ac/H2O2), sulfuric, hydrochloric and methanosulfuric acids as catalyzers, it was possible to obtain both compounds in a rapid and simple form. Raman, IR spectroscopy, and GC-MS were used in order to determine the precursors, intermediates and final analytes. Experiments and theoretical studies using density functional theory (DFT) have been used in the elucidation step of the mechanism of the synthesis of the so called "transparent" explosives. The B3LYP functional with the 6-31G** basis set was used to carry out the electronic structure calculation of the intermediates and internal rotations and vibrations of TATP. Raman spectra of solid TATP and FTIR spectra of gas TATP, were recorded in order to assign the experimental spectra. Although full agreement with experiment was not obtained, spectral features of the main TATP bands were assigned.

Atomic force microscopy (AFM), scanning electron microscopy (SEM), white light imaging measurements, and Raman microscopy were employed for the characterization of hexahydro-1,3,5-trinitro-1,3,5-s-triazine (RDX) nanoparticles deposited on glass substrate surfaces. The RDX nanoparticles were prepared by exposure of glass substrate surfaces to an aerosol jet containing RDX. The spectroscopic signature of RDX particles and the two known forms of the material, β and α RDX, are compared. Raman measurements reveal that RDX nanoparticles and β deposits have similar spectroscopic signatures between 750 and 1000 cm-1.

RDX, a high power explosive used as the main charge in some landmines, was investigated in our laboratory in order to determine the spectroscopic signature to be used in its identification by means of ion mobility spectrometry (IMS) and FTIR. Density functional theory (DFT) was also used to predict structural parameters and vibrational frequencies. It was confirmed that RDX has two conformers known as the and -RDX phases. There are several conformers depending on the position of the NO 2 groups with respect to the triazine ring. This is important in order to determine whether RDX will have affinity for soil and/or the different materials in the ground or will be carried out by water once it starts to leak from the container holding the explosives. Different amounts of RDX were deposited on soil, aluminum plates, glass, and vinyl polymeric films. For IMS studies, the surfaces were rubbed with filter paper and the RDX was desorbed directly from the filter to the instrument inlet port. In the case of the FT-IR studies the samples were examined using an ATR coupled FTIR system. The FTIR spectra showed significant differences between the and phases of RDX. Keywords: RDX chemical signature, explosives, FTIR, IMS, RDX interactions, RDX in soil. 1.

This legal reference covers in detail evidence used in trials to determine blood alcohol (ethanol) concentrations. The author covers evidence as used in criminal and civil trials. The two volumes are divided into ten parts. Part I covers alcohol consumption and the relation between absorption and elimination as well as other physiological considerations such as sex and food intake. Part II deals with calculations relating drinks and blood concentration, including a discussion of the variability in calculations that can be used in the defense’s best interest. Part III concerns …

The chain of custody may determine whether evidence is competent and, therefore, whether it is admissible. Laboratory reports and autopsy results are based on specimens that must be shown to be free of tampering before they can be allowed into evidence and/or used as a basis for testimony. Any report, result, or specimen maybe used as evidence regardless of whether the laboratory is forensic. The chain of custody used to authenticate evidence can be done by written documentation with the use of a single form or multiple forms including receipts. The chain can also be established with oral testimony or a combination of the above. Depending on the type of specimen and the importance attached to it by the court may determine the specific requirements of the chain of custody. Local custom in the jurisdiction is important in determining the type of documentation necessary.

This presentation covers a multiphasic approach to toxicological service. The service is to the hospital and the community as a whole. The optimization includes the analytical aspects of clinical, forensic, and industrial toxicology along with service associated with interpretations, chemical disasters and employee monitoring.