A calibration model was created to illustrate the detection capabilities of laser ablation molecular isotopic spectroscopy (LAMIS) discrimination in isotopic analysis. The sample set contained boric acid pellets that varied in isotopic concentrations of <sup>10</sup>B and <sup>11</sup>B. Each sample set was interrogated with a Q-switched Nd:YAG ablation laser operating at 532 nm. A minimum of four band heads of the β system B<sup>2</sup>∑ → Χ<sup>2</sup>∑transitions were identified and verified with previous literature on BO molecular emission lines. Isotopic shifts were observed in the spectra for each transition and used as the predictors in the calibration model. The spectra along with their respective 10/11B isotopic ratios were analyzed using Partial Least Squares Regression (PLSR). An IUPAC novel approach for determining a multivariate Limit of Detection (LOD) interval was used to predict the detection of the desired isotopic ratios. The predicted multivariate LOD is dependent on the variation of the instrumental signal and other composites in the calibration model space.
The need for robust, versatile, and rapid analysis standoff detection systems has emerged in response to the increasing threat to homeland security. Laser Induced Breakdown Spectroscopy (LIBS) has emerged as a novel technique that not only resolves issues of versatility, and rapid analysis, but also allows detection in settings not currently possible with existing methods. Several studies have shown that femtosecond lasers may have advantages over nanosecond lasers for LIBS analysis in terms of SNR. Furthermore, since femtosecond pulses can travel through the atmosphere as a self-propagating transient waveguide, they may have advantages over conventional stand-off LIBS approaches<sup>1</sup>. Utilizing single and multiple femtosecond pulse laser regimes, we investigate the potential of femtosecond LIBS as a standoff detection technology. We examine the character of UV and visible LIBS from various targets of defense and homeland security interest created by channeled femtosecond laser beams over distances of 30m or more.
Several plant species release volatile organic compounds (VOCs) when under stresses such as herbivore feeding attack.
The release of these plant-produced VOCs (i.e. terpenes) triggers the release of active biochemical defenses, which
target the attacker. In some cases, the VOCs send cues to nearby carnivorous predators to attract them to the feeding
herbivore. Volatile compounds are released both locally by damaged leaves and systemically by the rest of the plant.
These compounds are released in large quantities, which facilitate detection of pests in the field by parasitoids.
Detecting the plant’s VOC emissions as a function of various parameters (e.g. ambient temperature, atmospheric
nitrogen levels, etc.) is essential to designing effective biological control systems. In addition these VOC releases may
serve as early warning indicator of chemo-bio attacks. By combining Raman spectroscopy techniques with Laser
Remote Sensing (LIDAR) systems, we are developing a Standoff detection system. Initial results indicate that is it
possible to detect and differentiate between various terpenes, plant species, and other chemical compounds at distances
greater than 12 meters. Currently, the system uses the 2nd harmonic of a Nd:YAG; however plans are underway to
improve the Raman signal by moving the illumination wavelength into the solar-blind UV region. We report on our
initial efforts of designing and characterizing this in a laboratory proof of concept system. We envision that this effort
will lead to the design of a portable field-deployable system to rapidly characterize, with a high spatial resolution, large
crops and other fields.
The XM-1 soft x-ray microscope utilizes bending-magnet radiation from the Advanced Light Source in Berkeley, CA. This radiation is collected by a `large' (9 mm diameter) fresnel condenser zone plate which projects light through a pinhole and illuminates the sample. The radiation transmitted through the sample is then focused and magnified by a high-precision objective micro zone plate and recorded by a soft x-ray CCD camera. Our condenser zone plate and pinhole combination serves ad our adjustable monochromator for selecting the desired photon energy, giving us a (lambda) /(Delta) (lambda) of 700. This moderate spectral resolution allows for spectroscopic imaging with XM-1, including samples of magnetic materials with contrast provided by magnetic circular dichroism. Our user-friendly software programs allow for frequent utilization of complex image processing techniques.
Recent experimental results from an actinic EUVL mask blank defect inspection system are presented. Bright-field and dark-field scans from various programmed defect samples are reported. Our results show that the current system can detect defects as small as 0.2 micrometers . Substrate roughness is identified as the limitation to the detection sensitivity. A preliminary defect counting experiment is reported and future improvements for practical defect counting are discussed.
We report the design and initial experimental results of an actinic inspection system for extreme ultraviolet lithography mask blank defect detection. Initial bright-field and dark- field results demonstrate sensitivity to submicron size phase defects.