Quantum cascade laser back‐reflection spectroscopy at grazing‐angle incidence using the fast Fourier transform as a data preprocessing algorithm

• DOI: 10.1002/cem.3167
• Publication Date: 2019-07-29T11:58:31Z
• Authors: Leonardo C. Pache...; Nataly J. Galán‐F...; Amanda M, Figuero...; Ricardo Infante‐C...; José L. Ruiz‐Caba...; Samuel P. Hernánd...
• Keywords: Chemometrics; Quantum cascade laser; Fourier transform spectroscopy; Laser-induced breakdown spectroscopy

Abstract A simple optical layout for a grazing‐angle probe (GAP) mount coupling to midinfrared (MIR) quantum cascade laser (QCL) spectrometer is described. This assembly enables reflectance measurements at high incident angles. In the case of optically thin films and deposits on MIR reflective substrates, double‐pass effect occurs, which accompanied by absorption deposited samples in reflection‐absorption infrared spectroscopy modality. The system allows light pass through sample twice. Applications cleaning validation detection traces explosives using QCL‐GAP reported. Principal component analysis partial least squares multivariate chemometrics methods were employed analyze spectra evaluate an analytical methodology confirming presence residues pharmaceutically active ingredients (irbesartan) (cyclotrimethylenetrinitramine [RDX]) that have been metallic substrates. performance spectral preprocessing via fast Fourier transform (FFT) was evaluated ability extract more powerful accurate information from obtained spectra. According figures merit this new technique, FFT with chemometric routines can obtain sensitivity specificity values 1.000. limits irbesartan RDX 26 8 ng/cm 2 , respectively. experimental results demonstrate proposed system, when used together proper routines, constitutes tool development methodologies lower range applications involve detecting analytes reside substrates as contaminants.