Adsorbents for hydrogen-bond accepting hazardous chemicals by post-synthetic modification of UiO-66-NH.

Adsorbents for hydrogen-bond accepting chemicals such as organophosphates are developed by post-synthetically modifying UiO-66-NH through two analogous condensation reactions to incorporate hydrogen-bond donating adsorbent groups. When benzaldehydes are employed as coupling partners, the resulting imine-functionalized MOFs show improvements in uptake capacity with increasingly electron-deficient adsorbent groups. By contrast, when the coupling partners are benzoic acids, the resulting amide-functionalized MOFs exhibit improvements in uptake capacity with increasingly electron-rich adsorbent groups.

Simultaneous real-time spectroscopy using a broadband IR laser source.

In this study, we have developed a simultaneous grating spectroscopy using a broadband IR laser source capable of detecting moving targets in real time. The broadband IR laser source operated in pulsed mode provides a broad spectral range, which covers absorption bands of many chemical analytes. The laser operating conditions were optimized to cover the broadest wavelength range spanning spectral features for the analytes of interest, based on a detailed understanding of the broadband source.

Time resolved characterization of Fabry-Perot quantum cascade lasers for use in a broadband "white light" source.

We report the time resolved characterization of Fabry-Perot quantum cascade lasers (FP-QCLs). We are developing a custom-built broadband laser source in the Mid-LWIR range by combining several high power FP-QCLs for a single snap shot application. This white light source would enable not only stand-off detection applications in a single snapshot but also new data collection modalities such as live, real-time chemical imaging, requiring extremely rapid measurements.

Gas chromatography using a spin-coated stationary phase and a molded elastomer micro-channel.

Many different designs of microfabricated gas chromatography columns have recently been proposed and demonstrated. These designs either incorporate a stationary phase directly into the device which limits the versatility of the column as a separator, or require coating, which presents its own problems with determining the proper conditions for each different stationary phase a user may need. Here, we present a new approach: Uniformly spin coating a flat surface with the stationary phase and creating a column by pressing a lid, with micro-fabricated ridges, down onto the coated substrate.

Reduction of speckle noise and mitigation of beam wander in tunable external cavity quantum cascade lasers using rotating diamond/KBr pellet coupled with multimode fiber.

We experimentally demonstrate speckle noise reduction and beam wander mitigation by using a rotating diamond/KBr pellet and a multimode fiber (MMF). As the diamond/KBr diffuser is rotated, the reflected speckle images that are captured by an infrared camera are temporally averaged. We demonstrate 78% speckle noise reduction by averaging 25 frames, which is within 80% of the theoretical contrast reduction.

Ostwald's Rule of Stages and its role in CdSe quantum dot crystallization.

A century ago Ostwald described the "Rule of Stages" after deducing that crystal formation must occur through a series of intermediate crystallographic phases prior to formation of the final thermodynamically stable structure. Direct evidence of the Rule of Stages is lacking, and the theory has not been implemented to allow isolation of a selected structural phase. Here we report the role of Ostwald's Rule of Stages in the growth of CdSe quantum dots (QDs) from molecular precursors in the presence of hexadecylamine.

Ligand-passivated Eu:Y2O3 nanocrystals as a phosphor for white light emitting diodes.

Eu(III)-doped Y(2)O(3) nanocrystals are prepared by microwave synthetic methods as spherical 6.4 ± 1.5 nm nanocrystals with a cubic crystal structure.