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An approach for the passive standoff detection of surface contaminants by differential polarization FTIR spectrometry is proposed. The surface radiance modeling associated with the method is given. Unpolarized and polarized sensing measurements obtained with the CATSI sensor for the standoff detection of liquid agent VX deposited on high-reflectivity surfaces are presented. The analysis of results indicates that the differential polarization approach is well suited to mitigate sky radiance drifts, which favours unambiguous surface contaminant detections. An experimental and modeling study initiated to address the spectral polarization phenomenology is outlined. The design of an optimized FTIR sensor for differential polarization spectrometry measurements is discussed.

The objective of this paper is to show that explosives may potentially be detected by passive standoff FTIR radiometry. It is demonstrated that many explosives exhibit a signature (fingerprint) in the longwave infrared (LWIR) region (i.e., 8 – 14 μm). Simulations using the radiative transfer model, MODTRAN4, clearly suggest that such materials can be identified when a thermal contrast exists between the material and its environment. The explosives considered in this study include octogen (HMX), trinitrotoluene (TNT), cyclonite (RDX), and the plastic explosives, C-4 and Detasheet-C. In addition, passive FTIR measurements of HMX have been performed in the field at standoff distances up to 60 m. The development of a passive standoff detection capability based on FTIR radiometry may be a potentially useful addition to the arsenal of measurement techniques that currently exist for the detection and identification of explosive threats.

Plasma-polymerized 1-benzyl-2-methylimidazole (PPBMI) thin films have been deposited onto glass substrates by glow discharge technique. Scanning electron micrographs reveal that the surface morphology of PPBMI thin films is uniform and flawless. Fourier transform infrared spectroscopy analysis shows that the chemical composition of PPBMI films is different from that of the BMI. From the ultraviolet-visible spectra direct and indirect transition energy gaps were determined to be between 3.10 and 3.35 eV and 1.80 and 1.95 eV, respectively, for as-deposited PPBMI thin films of different thicknesses. Both direct and indirect transition energy gaps increase with increasing thickness and decrease upon heat treatment.

Inorganic heavy metal borate glasses were prepared through the melt quenching technique. Two sets of glasses were prepared, the compositions are (wt.%) 35Bi₂O₃+(50-x)B₂O₃+15Na₂O+xPbO, where x=0, 10, 20, 30 and 35MO+30Na₂O+35B₂O₃ (MO=Bi₂O₃, PbO, ZnO). The FTIR structural analysis was made. These glasses have different borate groups and it mainly depends on the modifier/metal ion concentration. The influence of heavy metal and transition metal ion on the borate network were also identified.

Cu incorporated amorphous carbon thin films have been prepared by DC-magnetron sputtering using a bi-component Cu-C composite target. The properties of the films have been investigated by X-ray diffraction, energy dispersive X-ray analysis, atomic force microscopy, FTIR, Raman and UV-vis spectroscopies. The results show that the films are amorphous with major distorted sp² graphite bonds as well as carbon nanotubes. Sputtering simulation shows that the chemical composition of the films is Cu_0.066C_0.934. Cu addition results in the formation of new type of carbon nanotubes (CNT) with new radial Breathing mode located at 236 cm^-1. Cu induces an increase in the density of defects due to bundles of CNT's. Moreover the films are transparent in visible range and highly reflective in mid-infrared region. Electrical characterization shows that the pure carbon deposited films are semiconductor while the copper assisted thin films behave like metal and their sheet resistance is comparable with sheet resistance of conventional conductive electrodes.

Silver nanoparticles (SNPs) have been successfully prepared using sol–gel method by annealing the sample at 550°C for 30 min. The SNPs were not confirmed by X-ray diffraction (XRD) analysis when the annealing temperature was considered at 450°C. They were also not confirmed without calcination of the sample. The physical mechanism of silver clusters formation in the densified silica matrix with respect to thermal treatment has been understood. The presence of silver metal in the silica matrix was confirmed by XRD analysis and TEM image of the samples. The average size of nanoparticles dispersed in silica matrix was determined as 10.2 nm by the XRD technique. The synthesized nanocomposites were also characterized by UV-Visible spectroscopy with a peak in the absorption spectra at around 375 nm. The distribution of particle size has been reported here in the range from 8 nm to 25 nm by TEM observations of the sample prepared at 550°C. The spherically smaller size (≈10 nm) SNPs have reported the surface plasmons resonance (SPR) peak less than or near to 400 nm due to blue-shifting and effect of local refractive index. Without annealing the silica samples the absorption spectra does not show any peak around 375 nm. The FTIR spectroscopy of the three types of samples prepared at different temperatures (room temperature, 450°C and 550°C) has also been reported. This spectra have provided the identification of different chemical groups in the prepared samples. It has been predicted that the size of SNPs by XRD, UV-Visible and TEM results have agreed well with each other. It may be concluded that formation of SNPs is a function of annealing temperature.

The usage of chemically-amplified, negative tone SU-8 photoresist is numerous, spanning industrial, scientific and medical fields. Hence, in this study, some preliminary studies were conducted to understand the dosage and heat treatment requirements of the SU-8 photoresist essential for pattern generation using X-ray lithography. In this work, using Synchrotron as the X-ray source, SU-8 photoresist was characterized for X-ray lithography in terms of its process parameters such as X-ray exposure dose, post exposure bake (PEB) time and temperature for various photoresist thicknesses which is considered worthwhile in view of applications of SU-8 for the fabrication of very high aspect ratio micro structures. The process parameters were varied and the resultant cross linking of the molecular chains of the photoresist was accurately monitored using a Fourier Transform Infra-Red (FTIR) spectrometer and the results are discussed. The infrared absorption peak at 914 cm^-1 in the spectrum of the SU-8 photoresist was found to be a useful indicator for the completion of cross linking in the SU-8 photoresist. Results show that the cross linking of the SU-8 photoresist is at a higher rate from 0 J/cm³ to 30 J/cm³ after which the peak almost saturates regardless of the PEB time. It is a good evidence for the validation of dosage requirement of SU-8 photoresist for effective completion of cross linking, which in turn is a requirement for efficient fabrication of micro and nano structures. An analogous behavior was also observed between the extent of cross linking and the PEB time and temperature. The rate of cross linking declines after a certain period of PEB time regardless of PEB temperature. The obtained results also show a definite relation between variation of the absorbance area of the peak at 914 cm^-1 and the X-ray exposure dose.

The vibrational properties of metal complexes of monoformylated and diformylated chlorophyll derivatives were compared with those of the corresponding free-base chlorins to unravel the effects of the central metal on the carbonyl stretching vibration modes of the peripheral oxygen functional groups in the chlorin macrocycle by means of FTIR spectroscopy. The 3-C=O stretching vibrational bands of a 3-formyl group were shifted to lower wavenumbers by insertion of Zn and Cu into the center of the 3-formyl free-base chlorin. In contrast, the 7- and 8-C=O stretching vibrational bands of the formyl groups linked to the B-ring of the chlorin macrocycle were barely shifted even if 7- and 8-formyl free-base chlorins were metalated. The down-shifts of the 3-C=O and few shifts of the 7-/8-C=O vibrational stretching bands were in line with the results of DFT calculations. The difference in the effects of the central metal on the vibrational properties between the formyl group in the A-ring and those in the B-ring is ascribable to the different conjugation manners with the adjacent π-system: the 3-formyl group was connected to the chlorin 18π-system, whereas the 7-/8-formyl groups were conjugated to the rather isolated C7–C8 double bond. The 13-C=O stretching vibrational bands were shifted to lower wavenumbers by metalation. These down-shifts can also be rationalized by invoking the conjugation of the 13-keto group with the chlorin 18π-system.

Attachment of synthetic analogs of natural tetrapyrroles to electroactive surfaces enables physicochemical interrogation and may provide material for use in catalysis, diagnostics, and energy conversion. Six synthetic zinc chlorins and one free base bacteriochlorin, tailored analogs of chlorophyll and bacteriochlorophyll, respectively, have been attached to Si(100) via a high-temperature (400°C) baking method. The hydroporphyrins bear diverse functional groups that enable surface attachment (vinyl, acetyl, triisopropylsilylethynyl, pentafluorophenyl, and hydroxymethylphenyl) and a geminal dimethyl group in each reduced ring for stabilization toward adventitious dehydrogenation. The films were examined by cyclic voltammetry, FTIR spectroscopy, X-ray photoelectron spectroscopy, and ellipsometry. Monofunctionalized and difunctionalized hydroporphyrins gave monolayer and multilayer films, respectively, indicating robustness of the hydroporphyrin molecules, but in each case the film was more heterogeneous than observed with comparable porphyrins. The data suggest that some amount of unattached molecules remain intercalated with surface-attached molecules. Additional molecular designs will need to be examined to develop a deep understanding of the structure-activity relationship for formation of homogeneous monolayers and multilayers of synthetic hydroporphyrins.

An approach for the passive standoff detection of surface contaminants by differential polarization FTIR spectrometry is proposed. The surface radiance modeling associated with the method is given. Unpolarized and polarized sensing measurements obtained with the CATSI sensor for the standoff detection of liquid agent VX deposited on high-reflectivity surfaces are presented. The analysis of results indicates that the differential polarization approach is well suited to mitigate sky radiance drifts, which favours unambiguous surface contaminant detections. An experimental and modeling study initiated to address the spectral polarization phenomenology is outlined. The design of an optimized FTIR sensor for differential polarization spectrometry measurements is discussed.

The objective of this paper is to show that explosives may potentially be detected by passive standoff FTIR radiometry. It is demonstrated that many explosives exhibit a signature (fingerprint) in the longwave infrared (LWIR) region (i.e., 8 – 14 μm). Simulations using the radiative transfer model, MODTRAN4, clearly suggest that such materials can be identified when a thermal contrast exists between the material and its environment. The explosives considered in this study include octogen (HMX), trinitrotoluene (TNT), cyclonite (RDX), and the plastic explosives, C-4 and Detasheet-C. In addition, passive FTIR measurements of HMX have been performed in the field at standoff distances up to 60 m. The development of a passive standoff detection capability based on FTIR radiometry may be a potentially useful addition to the arsenal of measurement techniques that currently exist for the detection and identification of explosive threats.