This PDF file contains the front matter associated with SPIE Proceedings Volume 7304, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Pathogenic ecology is the natural relationship to animate and inanimate components of the environment that support the sustainment of a pathogen in the environment or prohibit its sustainment, or their interactions with an introduced pathogen that allow for the establishment of disease in a new environment. The anthrax bacterium in the spore form has been recognized as a highly likely biological warfare or terrorist agent. The purpose of this work was to determine the environmental reservoir of Bacillus anthracis between outbreaks of anthrax and to examine the potential factors influencing the conversion of the Bacillus anthracis from a quiescent state to the disease causing state. Here we provide environmental and laboratory data for the cycling of Bacillus anthracis in plants to reconcile observations that contradict the soil borne hypothesis of anthrax maintenance in the environment.

Raman chemical imaging microspectroscopy (RCIM) is being evaluated as a technology for waterborne pathogen detection. Binary and ternary mixtures including combinations of polystyrene beads, Grampositive Bacillus anthracis and B. atrophaeus spores, B. cereus vegetative cells, and Gram-negative E. coli cells were investigated by RCIM for differentiation and characterization purposes. We have demonstrated the ability of RCIM, in combination with Pearson's cross correlation and multivariate principal components analysis data reduction techniques, to differentiate these components in the same field of view (FOV). Conventional applications of RCIM consist of differentiating relatively broad areas in a FOV. Here, RCIM is expanded in its capabilities to differentiate and distinguish between different micron size species in single particles and clusters of mixed species.

The detection of harmful chemicals and biological agents in real time is a critical need for protecting water quality. We studied the real-time effects of five environmental contaminants with differing modes of action (atrazine, pentachlorophenol, cadmium chloride, malathion, and potassium cyanide) on respiratory oxygen consumption in 2-day post-fertilization fathead minnow (Pimephales promelas) eggs. Our objective was to assess the sensitivity of fathead minnow eggs using the self-referencing micro-optrode technique to detect instantaneous changes in oxygen consumption after brief exposures to low concentrations of contaminants. Oxygen consumption data indicated that the technique is indeed sensitive enough to reliably detect physiological alterations induced by all contaminants. After 2 h of exposure, we identified significant increases in oxygen consumption upon exposure to pentachlorophenol (100 and 1000 μg/L), cadmium chloride (0.0002 and 0.002 μg/L), and atrazine (150 μg/L). In contrast, we observed a significant decrease in oxygen flux after exposures to potassium cyanide (5.2, 22, and 44 μg/L) and atrazine (1500 μg/L). No effects were detected after exposures to malathion (200 and 340 μg/L). We have also tested the sensitivity of Daphnia magna embryos as another animal model for real-time environmental biomonitoring. Our results are so far encouraging and support further development of this technology as a physiologically coupled biomonitoring tool for the detection of environmental toxicants.

The quality and safety of drinking water is of major importance for human life. Current analytical methods recognizing viable bacteria in potable water are time consuming due to a required cultivation step. Fast and automated detection of water borne pathogenic microorganisms with high sensitivity and selectivity is still a challenging task. We report on a novel biosensor system using micromechanical filters with nano sized pores to capture and enrich bacteria on the filter surface. Thus the accumulated organisms are accessible to different detection methods using fluorescent probes. Depending on the kind of detection - specific (identification of a certain species) or unspecific (total amount of cells) - different assays are applied. For non-specific detection we use fluorescent dyes that bind to or intercalate in the DNA molecules of the bacteria. Upon binding, the fluorescent signal of the dyes increases by a factor of 1000 or more. Additionally, we use enzyme substrates for the detection of active cells. The whole detection process is automated by integrating the microsieves into a fluidic system together with a high performance fluorescence detector. To ensure realistic conditions, real potable water, i.e. including particles, has been spiked with defined amounts of microorganisms. Thus, sampling, enriching and detection of microorganisms - all with a single micromechanical filter - is not only possible with ideal media, e.g. laboratory buffer solutions, but also with tap water. These results show the potential of microfilters for several applications in fast pathogen detection.

This paper highlights the distinctions between the infrared (IR) absorption spectra of vegetative versus sporulated Bacillus bacteria. It is observed that there are unique signatures clearly associated with either the sporulated or the vegetative state, and that vegetative cells (and associated debris) can contribute to the spore spectra. A distinct feature at ~1739 cm^-1 appears to be unique to vegetative cell spectra, and can also be used as an indicator of vegetative cells or cell debris in the spore spectra. The data indicate the band is caused by a phospholipid carbonyl bond and are consistent with, but do not prove it to be, either phosphatidyl ethanolamine (PE) or phosphatidyl glycerol (PG), the two major classes of phospholipids found in vegetative cells of Bacillus species. The endospore spectra show characteristic peaks at 1441, 1277, and 1015 cm^-1 along with a distinct quartet of peaks at 766, 725, 701, and 659 cm^-1. These are clearly associated with calcium dipicolinate trihydrate, CaDP•3H₂O. We emphasize that the spore peaks, especially the quartet, arise from the calcium dipicolinate trihydrate and not from dipicolinic acid or other dipicolinate hydrate salts. The CaDP•3H₂O vibrational peaks and the effects of hydration were studied using quantum chemistry in the PQS software package. The quartet is associated with many motions including contributions from the Ca²⁺ counterion and hydration waters including Ca-O-H bends, H₂O-Ca-O torsions and O-C-O bends. The 1441 and 1015 cm^-1 modes are planar pyridine modes with the 1441 mode primarily a ring C-N stretch and the 1015 mode primarily a ring C-C stretch.

Since this is the tenth Chemical and Biological Sensing Conference, it is timely to reflect on progress in this field. We present a perspective on biological standoff detection from the point of view of past and current programs at the Johns Hopkins University Applied Physics Laboratory. Topics will include our role in field testing, laboratory measurements and system modeling. We will also review the APL program in optical property determination of biological aerosols. Many challenges have been overcome and many lessons learned over the years that are worth reporting.

A chamber aerosol LIDAR is being developed to perform well-controlled tests of optical scattering characteristics of biological aerosols, including Bacillus atrophaeus (BG) and Bacillus thuringiensis (BT), for validation of optical scattering models. The 1.064 μm, sub-nanosecond pulse LIDAR allows sub-meter measurement resolution of particle depolarization ratio or backscattering cross-section at a 1 kHz repetition rate. Automated data acquisition provides the capability for real-time analysis or recording. Tests administered within the refereed 1 cubic meter chamber can provide high quality near-field backscatter measurements devoid of interference from entrance and exit window reflections. Initial chamber measurements of BG depolarization ratio are presented.

The complexity of biological agents can make it difficult to identify the important factors impacting scattering characteristics among variables such as size, shape, internal structure and biochemical composition, particle aggregation, and sample additives. This difficulty is exacerbated by the environmentally interactive nature of biological organisms. In particular, bacterial spores equilibrate with environmental humidity by absorption/desorption of water which can affect both the complex refractive index and the size/shape distributions of particles - two factors upon which scattering characteristics depend critically. Therefore accurate analysis of experimental data for determination of refractive index must take account of particle water content. First, spectral transmission measurements to determine visible refractive index done on suspensions of bacterial spores must account for water (or other solvent) uptake. Second, realistic calculations of aerosol scattering cross sections should consider effects of atmospheric humidity on particle water content, size and shape. In this work we demonstrate a method for determining refractive index of bacterial spores bacillus atropheus (BG), bacillus thuringiensis (BT) and bacillus anthracis Sterne (BAs) which accounts for these effects. Visible index is found from transmission measurements on aqueous and DMSO suspensions of particles, using an anomalous diffraction approximation. A simplified version of the anomalous diffraction theory is used to eliminate the need for knowledge of particle size. Results using this approach indicate the technique can be useful in determining the visible refractive index of particles when size and shape distributions are not well known but fall within the region of validity of anomalous dispersion theory.

This paper presents an overview of recent work by the Edgewood Chemical Biological Center (ECBC) in algorithm development for parameter estimation, detection, and classification of localized aerosols in the atmosphere using information provided by multiple-wavelength range-resolved lidar. The motivation for this work is the need to detect, locate, and identify potentially toxic atmospheric aerosols at safe standoff ranges using time-series data collected at a discrete set of CO₂ laser wavelengths. The paper describes examples this processing derived from an extensive set of data collected by ECBC during JBSDS field-testing at Dugway Proving Ground.

The overall aim is the realization of a reliable, ultrafast, and portable tool for the identification of B-agents at the point of interest. PCR is the method to be used for the doubtless identification of e.g. bacteria, and viruses. Miniaturization is the way to include the overall analysis process, from sample preparation to detection, on a microtiterplate-sized consumable device and to allow to carry out the analysis without the need for an equipped biological laboratory. The novel PCR concept with constant temperature zones allows also for the instrument to become portable, due to much reduced power consumption since no thermocycling is necessary. This paper focuses on the overall concept to implement the biological reactions for the analysis on-chip, the methods of sample preparation on-chip, and the results of the ultrafast PCR with B-agents on-chip, as well as the basic instrument.

An atmospheric chemistry model that describes the behavior and disposition of environmentally hazardous compounds discharged into the atmosphere was coupled with the transport and diffusion model, SCIPUFF. The atmospheric chemistry model was developed by reducing a detailed atmospheric chemistry mechanism to a simple empirical effective degradation rate term (k_eff) that is a function of important meteorological parameters such as solar flux, temperature, and cloud cover. Empirically derived k_eff functions that describe the degradation of target toxic industrial chemicals (TICs) were derived by statistically analyzing data generated from the detailed chemistry mechanism run over a wide range of (typical) atmospheric conditions. To assess and identify areas to improve the developed atmospheric chemistry model, sensitivity and uncertainty analyses were performed to (1) quantify the sensitivity of the model output (TIC concentrations) with respect to changes in the input parameters and (2) improve, where necessary, the quality of the input data based on sensitivity results. The model predictions were evaluated against experimental data. Chamber data were used to remove the complexities of dispersion in the atmosphere.

The Range Test Validation System (RTVS) includes a constellation of five AIRIS-WAD standoff multispectral sensors oriented around a 1000×1000 meter truth box at a range of 2700 meters. Column density data derived from these sensors is transmitted in real-time to a command post using a wireless network. The data is used with computed tomographic methods to produce 3-D cloud concentration profiles for chemical clouds traversing the box. These concentration profiles are used to provide referee capability for the evaluation of both point and standoff sensors under test. The system has been used to monitor chemical agent simulants released explosively as well as continuously through specialized stacks. The system has been demonstrated to accurately map chemical clouds with concentrations as low as 0.5 mg/m³ at spatial and temporal resolutions of 6 meters and 3 seconds.¹ Data products include geo-referenced cloud mass centroids and boundaries as well as total cloud mass.

A midwave infrared (MWIR) imaging Fourier transform spectrometer (FTS), the Telops FIRST-MWE (Field-portable Imaging Radiometric Spectrometer Technology - Midwave Extended) has been utilized for the standoff detection and characterization of chemical plumes. Successful collection and analysis of MWIR hyperspectral imagery of jet engine exhaust has allowed us to produce spatial profiles of both temperature and chemical constituent concentrations of exhaust plumes. Successful characterization of this high temperature combustion event has led to the collection and analysis of hyperspectral imagery of lower temperature emissions from industrial smokestacks. This paper presents MWIR data from remote collection of hyperspectral imagery of methyl salicilate (MeS), a chemical warfare agent simulant, during the Chemical Biological Distributed Early Warning System (CBDEWS) test at Dugway Proving Grounds, UT in 2008. The data did not contain spectral lines associated with emission of MeS. However, a few broad spectral features were present in the background-subtracted plume spectra. Further analysis will be required to assign these features, and determine the utility of MWIR hyperspectral imagery for analysis of chemical warfare agent plumes.

Photoacoustic spectroscopy (PAS) is a useful monitoring technique that is well suited for trace gas detection. This method routinely exhibits detection limits at the parts-per-million (ppm) or parts-per-billion (ppb) level for gaseous samples. PAS also possesses favorable detection characteristics when the system dimensions are scaled to a microsystem design. Micro-electromechanical systems (MEMS)-scale designs offer the possibility to develop photoacoustic sensors in which the signals would remain at sensitivities similar to or greater than those typically found in macro-scale devices. The objective of the present work is to develop a monolithic MEMS-scale photoacoustic trace gas sensor utilizing the Army Research Laboratory's chemical and biological sensing capability. In order to realize the advantage of photoacoustic sensor miniaturization, light sources of comparable size are required. Quantum cascade lasers (QCLs) have been tested in combination with MEMS-scale photoacoustic cells. This sensing platform has provided favorable detection limits for a standard nerve agent simulant. Current research employs this sensor scheme for the detection of 2,4-dinitrotoluene, a degradation product of TNT. Preliminary results describing the sensor capabilities and performance for the detection of this compound will be presented.

A new generation of field-rated optical subtraction instruments for the standoff detection of chemicals will be presented. It combines the latest ABB Bomem spectroradiometer technology and software with the concepts used in the design of the original instrument designed and manufactured more than 12 years ago by ABB and Defence Research and Development Canada - Valcartier. This instrument is a Fourier-transform spectroradiometer with dual input beams. It is a passive, stand-off sensor that uses one input port to interrogate a scene under investigation while the other input beam can be pointed at the background scene. The instrument automatically measures the difference of spectral radiance between the target and the background scenes by optical subtraction, hence achieving a real-time suppression of the background signal. The resulting measurement is the unique spectral signature of the target measured in real time. The system includes a software module to control the instrument and the acquisition parameters, a module for the radiometric calibration and a module to perform the identification and quantification, in real time, of various gases. An overview of the instrument design and initial results of tests are presented.

The non-contact detection of chemical warfare agent simulants is achieved in the condensed phase using polarization modulation infrared reflection-absorption spectroscopy (PMIRRAS). The G-series nerve agent simulants, trimethyl phosphate (TMP) and triethyl phosphate (TEP), are detected on US military chemical agent resistant coating (CARC) using PMIRRAS. Optimal detector angles for PMIRRAS are determined, as are absorption features which can be used to distinguish between the spectral contributions of the substrate (CARC) and the analyte (TMP or TEP). Ab initio calculations carried out at the B3LYP / 6-31G(d,p) level of theory and basis set are used to predict the most stable simulant conformations, and their harmonic (unscaled) vibrational frequencies. Ab initio vibrational frequency data is used to explain the existence of both upward-oriented and downward-oriented PMIRRAS absorption features in terms of molecular orientation at a surface and the orientation of the dipole derivative vector of a given vibrational mode.

Atmospheric discharge cold plasmas have been shown to be effective in the reduction of pathogenic bacteria and spores and in the decontamination of simulated chemical warfare agents, without the generation of toxic or harmful by-products. Cold plasmas may also be useful in assisting cleanup of radiological "dirty bombs." For practical applications in realistic scenarios, the plasma applicator must have both a large area of coverage, and a reasonably short dwell time. However, the literature contains a wide range of reported dwell times, from a few seconds to several minutes, needed to achieve a given level of reduction. This is largely due to different experimental conditions, and especially, different methods of generating the decontaminating plasma. We consider these different approaches and attempt to draw equivalencies among them, and use this to develop requirements for a practical, field-deployable plasma decontamination system. A plasma applicator with 12 square inches area and integral high voltage, high frequency generator is described.

OPTRA is developing an imaging open-path Fourier transform infrared (I-OP-FTIR) spectrometer for 3D profiling of chemical and biological agent simulant plumes released into test ranges and chambers. An array of I-OP-FTIR instruments positioned around the perimeter of the test site, in concert with advanced spectroscopic algorithms, enables real time tomographic reconstruction of the plume. The approach is intended as a referee measurement for test ranges and chambers. This Small Business Technology Transfer (STTR) effort combines the instrumentation and spectroscopic capabilities of OPTRA, Inc. with the computed tomographic expertise of the University of North Carolina, Chapel Hill.

Fourier transform infrared spectroscopy is a standard technique for remote detection of gaseous vapors. However, as algorithms mature and hyperspectral imaging in the longwave infrared becomes more prominent in ground based applications it is important to determine optimum parameters for detection due to potentially high data rates. One parameter, spectral resolution, is of particular interest because 1) it can be easily changed and 2) it has significant effect on the data rate. The following presents a mathematical foundation for determining the spectral resolution for vapor detection in the presence of atmospheric interferants such as water vapor and ozone. Results are validated using real-world long wave infrared hyperspectral data of several open air chemical simulant releases.

Multiwalled carbon nanotubes (MWCNTs) were chemically modified with a ferrocene-lysine conjugate and the material was deposited on indium tin oxide (ITO) and the surfaces were evaluated for their ability to act as electrochemical sensors for chemical warfare agent (CWA) mimics methylphosphonic acid (MPA), ethylmethylphosphonate (EMP) and diethyl cyanophosphonate (DECP).

Through an internally funded research program, Defiant Technologies has developed a compact chemical detector that can be tailored for a range of target analytes. The system uses a preconcentrator (PC) to collect and screen samples from the air, and a surface acoustic wave (SAW) microbalance to detect analytes when they are released from the PC. This PC-SAW system serves as a trigger for a secondary analysis channel that uses a micro-gas chromatographic (micro-GC) column to perform a more detailed analysis of the air. This combined approach provides high-confidence results while conserving power and minimizing response time. By properly selecting coatings on the PC, micro-GC and SAW, the unit can be designed for optimum performance in detecting specific target gases while ignoring interferents. This paper presents test results from our research and discusses some of the applications for this type of system.

We propose a new concept for point and stand-off detection of chemical and biological agents as well as explosives' vapors and residues on solid surfaces based on frequency comb spectroscopy in the region of mid-IR molecular vibrational "fingerprints". Our method will allow identification of hazardous substances with high detection sensitivity and real-time data processing. A two-octave-wide mid-infrared frequency comb output will be produced by a cascaded sub-harmonic optical parametric oscillator (OPO) pumped by a fiber laser. The proposed device will use the principle of coherent Fourier-transform infrared spectrometer and offer an unprecedented precision and speed of acquisition of spectral information.

Laser detection technologies offer obvious benefits for the standoff detection of hazardous or energetic materials where safe detection at a distance is the goal. Of the many optical standoff detection methods available, multiphoton fluorescence techniques have been studied less extensively. Multiphoton fluorescence allows high selectivity relative to the background while preserving the larger signal of laser induced fluorescence (LIF). Using sodium vapor as a test system, we demonstrate that stimulated Raman adiabatic passage (STIRAP) is capable of providing more than a factor of ten improvement in population transfer efficiency to the final state when compared to stimulated emission pumping (SEP). The two sodium transitions used are the 3p (²P_1/2) ← 3s (²S_1/2) and 5s (²S_1/2) ← 3p (²P_1/2). The light used to couple the states was produced with two synchronously pumped OPG/OPAs pumped by the 355 nm light from a picosecond tripled Nd:YAG.

Laser Induced Spectroscopy (LIBS) and Cavity Ring Down Spectroscopy (CRDS) are promising chemical sensor technologies for small mobile robotic platforms. LIBS leverages the natural surface adsorption from the atmosphere to interior and exterior surfaces for signal enhancement. In this work, a material or class-specific adsorption surface is combined with a miniature version of a CRDS ring cavity to achieve a similar signal enhancement for CRDS. The combination of LIBS and CRDS allow the analysis of both classes of materials - those with long adsorption times to permanent surfaces such as walls and those that require real time sampling of ambient concentrations. This paper emphasizes issues related to package miniaturization, power budget limitations and ruggedness as well as basic performance modeling of the instruments. Comprehensive sensing issues for material specific micro-detectors will be addressed. Computer simulations and some data are presented. Applications considered include the determination of need for remediation and the determination of the effectiveness of remediation techniques as well as the detection of hazards and intelligence gathering.

The paper describes the experiences in Italy with the CBRN (Chemical Biological Radiological Nuclear) defense mobile laboratories. These laboratories were constructed by the Italian Army and the Italian Fire Brigades. The purpose of these mobile laboratories is to allow quick transport of the labs to the area of crisis in order to support emergency response in case of CBRN events. The differences between two alternative solutions will be developed in the paper. The first solution is when the lab is to be located in the "dangerous area" (this solution was chosen by the Italian Army) and the alternative approach is to place the mobile lab just outside the dangerous area (this approach was selected by the Italian Fire Brigades). One of the most important devices inside the lab is the isolator (also called "glove box") which allows safe ingress and handling of the "suspicious" samples from the external environment. The isolator has a special chamber for transfer of the sample from the outside. The pressure of the isolator is permanently kept below the air pressure inside the lab by means of one (or more) fan. The operators perform the sample preparations or part of the analysis by handling the sample with the gloves. The material flow inside the lab will be described depending on the kind of identification analysis to be done on the samples. Other devices installed on the mobile CBRN laboratories are: biohazard hood (UE regulation, containment level 2); autoclave; freezer; cleaning skid (tanks, pumps, etc.).

The AIRIS Wide Area Detector is an imaging multispectral sensor that has been successfully tested in both ground and airborne configurations for the detection of chemical and biological agent simulants. The sensor is based on the use of a Fabry-Perot based tunable filter with a 256x256 pixel HgCdTe focal plane array providing a 32x32 degree field of regard with 10 meter spatial resolution at a range of 5 km. The sensor includes a real-time processor that produces an infrared image of the scene under interrogation overlaid with color-coded pixels indicating the identity and location of simulants detected by the sensor. We review test data from this sensor taken at Dstl Porton Down, NSWC Dahlgren, as well as from multiple test entries at Dugway Proving Ground. The data indicate the ability to detect release quantities from 0.15 to 360 kg at ranges of ~ 4.7 km including simultaneous multi-simulant releases.

Photon Systems and JPL are continuing development of a new technology robot-mounted or hand-held sensor for reagentless, short-range, standoff detection and identification of trace levels CBE materials on surfaces. This deep ultraviolet CBE sensor is the result of ongoing Army STTR and DTRA programs. The evolving 6 lb, 15W, lantern-size sensor can discriminate CBE from background clutter materials using a combination of deep UV excited resonance Raman (RR) and laser induced native fluorescence (LINF) emissions resulting from excitation by a new technology deep UV laser. Standoff excitation of suspicious packages, vehicles, persons, and other objects that may contain hazardous materials is accomplished using wavelengths below 250nm where RR and LINF emissions occupy distinctly different wavelength regions. This enables simultaneous detection of RR and LINF emissions with no spectral overlap or interference of LINF over RR or RR over LINF. The new eye-safe targeted ultraviolet chemical, biological, and explosives (TUCBE) sensor can detect and identify less than 1 μg/cm² of explosives or 10⁴ bacterial spores at 10 meters standoff, or 10 ng/cm² of explosives or 10² bacterial spores/cm² at 1 meter standoff. Detection and identification requires less than 1 ms and has a sample rate up to 20 Hz. Lower concentrations of contamination can be detected and identified as closer ranges and higher concentrations at longer ranges. The sensor is solar blind and can be operated in full daylight conditions as a result of excitation and detection in the deep UV and the use of a gated detection system.

Photomultiplier tubes (PMTs) are used in biological detection systems in order to detect the presence of biological warfare agents. To ensure proper operation of these biological detection systems, the performance of PMTs must be characterized in terms of their responsivity and long-term stability. We report a technique for PMT calibration at the Synchrotron Ultraviolet Radiation Facility (SURF III) at the National Institute of Standards and Technology (NIST). SURF III provides synchrotron radiation with a smooth and continuous spectrum covering the entire UV range for accurate PMT measurements. By taking advantage of the ten decade variability in the flux of the synchrotron radiation, we studied properties of commercial PMTs such as the linearity, spatial uniformity, and spectral responsivity. We demonstrate the degradation of PMTs by comparing new PMTs with PMTs that were used and operated in a biological detection system for a long period of time. The observed degradation is discussed.

Miniaturized field-deployable spectrometers used for the rapid analysis of chemical and biological substances require high-sensitivity photo detectors. For example, in a Raman spectroscopy system, the receiver must be capable of high-gain, low-noise detection performance due to the intrinsically weak signals produced by the Raman effects of most substances. We are developing a novel, high-gain hetero-junction phototransistor (HPT) detector which employs two nano-structures simultaneously to achieve 100 times higher sensitivity than InGaAs avalanche photodiodes, the most sensitive commercially available photo-detector in the near infrared (NIR) wavelength range, under their normal operation conditions. Integrated into a detector array, this technology has application for Laser- Induced Breakdown Spectroscopy (LIBS), pollution monitoring, pharmaceutical manufacturing by reaction monitoring, chemical & biological transportation safety, and bio-chemical analysis in planetary exploration.

The detection of explosives is a notoriously difficult problem, especially at stand-off distances, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring optimal dynamic detection to exploit the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity of explosives signatures while reducing the influence of noise and the signals from background interferents in the field (increase selectivity). These goals are being addressed by operating in an optimal nonlinear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked control and probe sub-pulses. With sufficient bandwidth, the technique is capable of intrinsically providing orthogonal broad spectral information for data fusion, all from a single optimal pulse.

Despite its renewed interest, remote sensing of explosives has proven to be difficult due to the low vapor pressure of the agents. In this paper we discuss a method to detect residue of explosive agents on fabric and clothing using Multi Spectral Imaging. Such a technique will aid in the detection of bomb making activities and individuals. While limited to line of sight only, Multi Spectral Imaging has much to recommend it including inspection of clothing in public places, luggage, and potential locations for bomb manufacture. This paper presents the basic techniques developed for detection of trace TNT and reports the results of several limited field trials. Imaging hardware is discussed and processing methodology is reviewed with some demonstrations of the identification difficulty for explosives and other false targets commonly found. The use of other spectral bands is presented with the goal of eliminating common false targets.

The midwave and shortwave infrared regions of the electromagnetic spectrum contain rich information enabling the characterization of hot, rapid events such as explosions, engine plumes, flares and other combustion events. High-speed sensors are required to analyze the content of such rapidly evolving targets. Cameras with high frame rates and non-imaging spectrometers with high data rates are typically used; however the information from these two types of instruments must be later fused to enable characterization of the transient targets. Imaging spectrometers have recently become commercially available for general scientific use, thus enabling simultaneous capture of both spatial and spectral information without co-registration issues. However, their use against rapidly-varying sources has traditionally been considered problematic, for even at moderate spatial and spectral resolutions the time to acquire a single spectrum can be long compared to the timescales associated with combustion events. This paper demonstrates that imaging Fourier-transform spectroscopy (IFTS) can successfully characterize the turbulent combustion exhaust from a turbojet engine. A Telops Hyper-Cam IFTS collected hyperspectral video from a Turbine Technologies SR-30 turbojet engine with a spectral resolution of δν = 1/cm^-1 on a 200×64 pixel sub-window at a rate of 0.3 Hz. Scene-change artifacts (SCAs) are present in the spectra; however, the stochastic fluctuations in source intensity translate into high-frequency "noise." Temporal averaging affords a significant reduction of the noise associated with SCAs. Emission from CO and CO₂ are clearly recognized in the averaged spectra, and information about their temperature and relative concentrations is evident.

We have developed a technique for the stand-off detection of trace explosives using infrared photothermal imaging. In this approach, infrared quantum cascade lasers tuned to strong vibrational absorption bands of the explosive particles illuminate a surface of interest, preferentially heating the explosives material. An infrared focal plane array is used to image the surface and detect a small increase in the thermal intensity upon laser illumination. We have demonstrated the technique using TNT and RDX residues at several meters of stand-off distance under laboratory conditions, while operating the lasers below the eye-safe intensity limit. Sensitivity to explosives traces as small as a single grain (~100 ng) of TNT has been demonstrated using an uncooled bolometer array. We show the viability of this approach on a variety of surfaces which transmit, reflect or absorb the infrared laser light and have a range of thermal conductivities. By varying the incident wavelength slightly, we demonstrate selectivity between TNT and RDX. Using a sequence of lasers at different wavelengths, we increase both sensitivity and selectivity while reducing the false alarm rate. At higher energy levels we also show it is possible to generate vapor from solid materials with inherently low vapor pressures.

Research with canines suggests that sniffer dogs alert not on the odor from a pure explosive, but rather on a set of far more volatile species present in an explosive as impurities. Following the explosive trained canine example, we have begun examining the vapor signatures for many of these volatile impurities utilizing high resolution spectroscopic techniques in several molecular fingerprint regions. Here we will describe some of these high resolution measurements and discuss strategies for selecting useful spectral signature regions for individual molecular markers of interest.

We demonstrate a prototype sensor based on a new eye-safe detection strategy with the potential to report the presence trace explosives from standoff distances of up to 100 m. The method detects the reflected infrared radiation from groups of micron-sized chemically-sensitized metallodielectric nanostructures. Specifically, the sensors change from reflecting to absorbing nearly 100% of the incident probe beam radiation over a narrow band of mid-IR wavelengths when explosive vapor is present. This strategy is not limited to the detection to explosives, but can also be used to detect other threats by modifying the chemically-sensitive layers of the nanostructure.

A fully integrated UV Townsend Effect Plasma Spectroscopy (TEPS)-Raman Explosive Detection System (TREDS-2) system has been constructed for use of standoff detection. A single 266nm Q-Switched Nd:YAG laser was used for Raman excitation and TEPS plasma ignition. A nearly simultaneous 10.6μm CO₂ laser was employed for the signal enhancement in the TEPS measurements. TEPS and Raman spectra have been measured for a wide variety of energetic samples on several different substrates. Chemometric techniques are presented for analysis and differentiation between benign and energetic samples. Since these techniques are orthogonal, data fusion algorithms can be applied to enhance the results. The results of the TEPS and Raman techniques along with their algorithms are discussed and presented.

The present work focuses on a new variant of double pulse laser induced breakdown spectroscopy (DP-LIBS) called Townsend effect plasma spectroscopy (TEPS) for standoff applications. In the TEPS technique, the atomic and molecular emission lines are enhanced by a factor on the order of 25 to 300 times over LIBS, depending upon the emission lines observed. As a result, it is possible to extend the range of laser induced plasma techniques beyond LIBS and DP-LIBS for the detection of CBRNE materials at distances of several meters.

This study makes a comparison of LIBS emission from molecular species in plasmas produced from organic residues on a non-metallic substrate by both a 5 ns Nd:YAG laser (1064 nm) and a 40 fs Ti:Sapphire laser (800 nm) in air and argon atmospheres. The organic samples analyzed had varying amounts of carbon, nitrogen, hydrogen, and oxygen in their molecular structure. The characterization was based on the atomic carbon, hydrogen, nitrogen, and oxygen lines as well as the diatomic species CN (B²Σ⁺ - X²Σ⁺) and the C₂ (d³Π_g - a³Π_u). Principal Component Analysis (PCA) was used to identify similarities of the organic analyte via the emission spectra. The corresponding Receiver Operating Characteristics (ROC) curves show the limitations of the PCA model for the nanosecond regime in air.

A new concept for effective sampling and detecting HME powder traces is described. The collection is based on the particles mobility under rotation into an accumulation collector unit, followed by sequential transfer to the electrochemical detection system where surface washing yields a higher concentration at room temperature. The electrochemical detection of the peroxide explosives is based on photochemical degradation or acid treatment resulting in hydrogen peroxide which is sensed by a Prussian-blue (PB) modified strip electrode at a low potential. Nitrates such as Urea Nitrate are detected using unique reactions which generate one product which has a specific electrochemical signature. Nitroaromatics, nitramines and nitroesters are detected. The new "Add and Detect" procedure is operator independent and is the safest as the operator.

Laser Induced Breakdown Spectroscopy (LIBS) by self-channeled femtosecond pulses is characterized for detection of energetic materials. Different polymers are spin coated on silicon wafers to provide a thin organic layer with controllable thickness ranging from 500 nm to 1 μm. Spectral analysis of atomic and molecular carbon emission shows CN molecular signal from samples that do not contain nitrogen. This can be explained by possible molecular recombination between native atomic carbon and atmospheric nitrogen. As a consequence, caution must be exercised when using spectral signatures based on CN emission for explosive detection by filament-induced LIBS.

Detection of explosives by ion mobility spectroscopy has become common in recent years. We demonstrate explosive detection with a novel Laser Ion Mobility Spectrometer (LIMS) developed at EADS Innovation Works. A Laser operating at 266nm was used for the two-photon ionisation of dopant and calibrant substances. Quantitative measurements of trace residues of explosives have been performed to quantify the sensitivity of the LIMS system. Findings demonstrate the suitability of this technique as a screening tool for explosive compounds.

This paper provides a brief overview of radiation detector history, a summary of the present state of the art, and some speculation on future developments in this field. Trends in the development of radiation detectors over the years are analyzed. Rapid progress in detection technology was experienced between WWII and the 1970s. Since then, fewer dramatic improvements have been seen. The authors speculate about the reasons for this trend and where the technology might take us in the next 20 years. Requirements for radiation detection equipment have changed drastically since 9/11; this demand is likely to accelerate detector development in the near future.

A brief overview of an AWE survey of existing techniques to detect SNM will be presented. This survey has identified two techniques that incorporate active gamma sources for further study. These are a photonuclear based technique and the use of nuclear resonance fluorescence. The current status of work in the development of these techniques is presented. Developments in physics modelling capabilities, active source technologies, detector technologies and data fusion and analysis approaches are summarised. Particular attention will be given to the potential for high current, pulsed power based, active interrogation sources for remote detection of SNM.

Active interrogation techniques using photons (<10 MeV) and low energy neutrons are currently being investigated at AWE for the remote detection of special nuclear material (SNM). To identify the presence of SNM the induced fission signatures are measured. AWE is investigating the combination of the photon and neutron techniques to provide robust detection for shielded scenarios involving either hydrogenous or high Z materials. A brief description of the interrogation sources is given with consideration to the extraction of high fidelity fission signatures in the presence of typical naturally occurring radioactive material and other background signals generated by the interrogation process. Initial results are presented from MCNPX simulations of prompt and delayed neutrons and γ-rays produced from the induced fission of SNM. Photon and low energy neutron interrogation simulations are compared to identify requirements for an initial common detection system.

Lead-iodide-based PbI₂, PbIOH and Pb₃O₂I₂ nanocrystals were synthesized by various chemical and mechanochemical solution methods. The nanocrystals were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), dynamic light scattering (DLS), steady-state UV-visible optical absorption and photoluminescence spectroscopy, and by photoluminescence lifetime and quantum efficiency measurements. Scintillation tests were performed on the lead-iodide based material exposed to low-level gamma irradiation.