The application of attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectromicroscopy for detection of explosive particles in fingerprints is described. The combined functions of ATR-FTIR spectromicroscopy are visual searching of particles in fingerprints and measuring the FTIR spectra of the particles. These functions make it possible to directly identify whether a suspect has handled explosives from the fingerprints alone. Particles in explosive contaminated fingerprints are either ingredients of the explosives, finger residues, or other foreign materials. These cannot normally be discriminated by their morphology alone. ATR-FTIR spectra can provide both particle morphology and composition. Fingerprints analyzed by ATR-FTIR can be used for further analysis and identification because of its non-destructive character. Fingerprints contaminated with three different types of explosives, or potential explosives, have been analyzed herein. An infrared spectral library was searched in order to identify the explosive residues. The acquired spectra are compared to those of finger residue alone, in order to differentiate such residue from explosive residue.

The techniques of atomic force microscopy (AFM) and Fourier transform infrared attenuated total reflectance (FTIR ⁄ ATR) spectroscopy are applied to the analysis of gun-shot residue (GSR) to test their ability to determine shooting distance and discrimination of the powder manufacturers. AFM is a nondestructive technique that is capable of characterizing the shapes and size distributions of GSR particles with resolution down to less than a nanometer. This may be useful for estimation of the shooting distance. Our AFM images of GSR show that the size distribution of the particles is inversely proportional to the shooting distance. Discrimination of powder manufacturers is tested by FTIR ⁄ ATR investigation of GSR. Identifying the specific compounds in the GSR by FTIR ⁄ ATR was not possible because it is a mixture of the debris of several compounds that compose the residue. However, it is shown that the GSR from different cartridges has characteristic FTIR ⁄ ATR bands that may be useful in differentiating the powder manufacturers. It appears promising that the development of AFM and FTIR ⁄ ATR databases for various powder manufacturers may be useful in analysis and identification of GSR.

Electric field-modulated amplified spontaneous emission in waveguides based on poly [2-methoxy-5-( 2 ′ethylhexyloxy)-1, 4-phenylene vinylene] Appl.Poly͑p-phenylene vinylene͒ mulilayers have been prepared from its cationic precursor via the layer-by-layer deposition. The photoluminescence ͑PL͒ and film thickness of the multilayers have been examined via fluorimetry and atomic force microscopy. The PL of the multilayers has been observed that is consistent with the literature results. When phosphomolybdate PMo 12 is incorporated into the multilayer structure, PL quenching is detected that is proportional to the amount of PMo 12 used. The quenching is interpreted as exciton diffusion through the polymer multilayers, followed by exciton dissociation at the polymer/PMo 12 interface. We show that the modeling used for calculating the PL intensities derived from inorganic semiconductors is also applicable to conjugated polymers. According to the model, an exciton diffusion length is found to be 11.5± 0.4 nm.