Microtech Instruments (United States)

Abstract Surface‐enhanced Raman spectroscopy (SERS) is a rapidly emerging technology that offers a fast, extremely sensitive, and quantitative approach to trace chemical detection. Such a technique incorporated into a portable device is attractive to law enforcement and emergency room personnel for rapid accurate on‐site screening of illicit and abused drugs. Toward this, we are developing an analyzer in a hand‐held unit, based on SERS that is integrated with a capillary sensor embedded with activated gold nanoparticles in a porous glass matrix. In this preliminary study, we have used this gold sol–gel capillary to measure aqueous solutions of 14 high‐priority drugs to define sensitivity (lowest measured concentration [LMC] and estimated limit of detection [LOD]), determine concentration dependence and quantification capabilities by constructing calibration curves, examine effects of pH at 3, 7, and 11 on SERS measurements, and perform multicomponent analysis of fentanyl laced drug mixtures and spectral identification on our portable and handheld units. Of particular significance, fentanyl was detected with an LMC of 1 ng/ml and estimated LOD at 0.11 ng/ml, while other representative drugs such as cocaine and phenylcyclidine produced LMCs and LODs at 5.0 and 0.77 ng/ml, and 10.0 and 0.62 ng/ml, respectively. These sub‐nanogram per milliliter detection limits are comparable or lower than previously reported and confirm that this gold sol–gel has the potential to meet the sensitivity requirements for saliva analysis. Most importantly, these sensors can be manufactured easily and cheaply and when integrated with our portable Raman units produce high‐quality spectra and accurate identification within 1.2 s.

We demonstrate frequency domain THz anisotropy signature detection for protein crystal models using newly developed compact tunable narrow band THz sources based on Orientation Patterned Gallium Phosphide for turn-key spectroscopic systems.

We demonstrate THz anisotropy signature determination of a protein crystal model using newly developed compact tunable narrow band THz sources for turn-key spectroscopic systems for the bio molecular community.

We demonstrate tunable, narrowband THz generation by optical rectification of a femtosecond pulse in orientation patterned gallium phosphide. Center frequencies from 0.9 – 3.8 THz with average power up to 15 μW were obtained.

The operating frequency range of millimeter wave Backward Wave Oscillators (BWOs) are extended to 2.2 THz using solid state frequency multipliers, enabling continuously tunable, narrow linewidth THz sources across the 0.1-2.2 THz range. Power conversion efficiency of frequency multipliers was improved substantially by optimizing impedance matching between the BWOs, multipliers, and free space. Impedance matching extracts more THz power out of BWOs coupled to frequency multipliers, than is emitted from BWOs radiating into free space.

We review nonlinear-optical applications of micro-structured quasi-phase matched GaAs. These include new sources of mid-IR coherent radiation, pump-polarization-insensitive devices, as well as sources of tunable terahertz radiation, based on optical rectification or intracavity frequency mixing.

Abstract Variation of molar mix ratio of the Epon 828/Diamino‐diphenyl sulfone (DDS) system was found to have significant influences on pre‐cure and post‐cure properties. Microdielectrometry showed that dielectric constant varies from about 9 to above 30 depending on DDS content before cure. Times to the 10 kHz loss peak during cures at 177°C were found to decrease with increasing DDS content. Above a ratio of 2/1 and below 1/2, due to the low molecular weight of the reaction products, loss peaks did not occur. Ionic conduction was shown to have a strong correlation with calorimetric kinetic cure data. The influence of both excess amine and excess DDS was to produce cured material with high ionic conduction levels indicative of loose networks. Deviations from ideal stoichiometry as small as 1.1/1 produced noticable differences in the finally cured network.