Molecular Laser Spectroscopy as a Tool for Gas Analysis Applications
Figure 4
Intrapulse chirp spectroscopy. (a) Data from the reference channel, without CO absorption (dashed line) and the sample channel (full line) featuring CO absorption, respectively. (b) Etalon transmission signal seen by detector 1 with the etalon ( cm−1) placed in the reference beam path. (c) and (d) Data transferred to the wave number domain. (c) Etalon transmittance curve. (d) Data of (a), converted to absorbance values. A Voigt profile has been fitted to the data (full line) representing the CO-P(1) line at 2139.43 cm−1. (e) The residuals from the fitted line in (d). QCL operating parameters: QCL substrate temperature 295 K, pulse length 255 ns, laser voltage 10.5 V, repetition rate 2 kHz, QCL chip: Fraunhofer-IAF (Fraunhofer Institut für Angewandte Festkörperforschung IAF, Freiburg, Germany, http://www.iaf.fraunhofer.de/). (f) Generalized linear regression of versus .
