Spectrochim Acta A Mol Biomol Spectrosc
April 2022
The infrared (IR) spectra of fentanyl, carfentanil and remifentanil, and protonated salts, are computed using quantum chemistry methods. New experimental FTIR spectra are also reported and compared to the calculations. The accuracy of two density functional theory methods, B3LYP and M06-2X, are tested against higher level theories (MP2) and the experimental data.
View Article and Find Full Text PDFInfrared spectroscopy in the spectral fingerprint region from 6.5 to 20 µm has been applied for decades to identify vapor- and condensed-phase chemicals with high confidence. By employing a unique broadband laser operating from 7.
View Article and Find Full Text PDFThis article presents new spectroscopic results in standoff chemical detection that are enabled by monolithic arrays of Distributed Feedback (DFB) Quantum Cascade Lasers (QCLs), with each array element at a slightly different wavelength than its neighbor. The standoff analysis of analyte/substrate pairs requires a laser source with characteristics offered uniquely by a QCL Array. This is particularly true for time-evolving liquid chemical warfare agent (CWA) analysis.
View Article and Find Full Text PDFWe presented the first demonstration of stand-off Fourier transform infrared (FTIR) spectroscopy using a broadband mid-infrared optical parametric oscillator, with spectral coverage over 2700-3200 cm⁻¹. For vapor-phase water and nitromethane (NM), stand-off spectra was recorded using a concrete target at from 1-m to 2-m range and showed good agreement with reference spectra, and in NM a normalized detection sensitivity of 15 ppm·m·Hz(-1/2) was obtained. Spectra from 50-μL droplets of liquid thiodiglycol were detected at a stand-off distance of 2 m from aluminum, concrete and painted metal surfaces.
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