caa a22 4500 445372257 CHVBK 20180317142951.0 cr unu---uuuuu 170323e20110301xx s 000 0 eng 10.1007/s00340-010-4259-4 doi (NATIONALLICENCE)springer-10.1007/s00340-010-4259-4 A quantum cascade laser-based optical feedback cavity-enhanced absorption spectrometer for the simultaneous measurement ofCH4 and N2O in air [Elektronische Daten] [D. Hamilton, A. Orr-Ewing] Optical feedback cavity-enhanced absorption spectroscopy (OF CEAS) has been demonstrated with a thermoelectrically cooled continuous wave distributed feedback quantum cascade laser (QCL) operating at wavelengths around 7.84μm. The QCL is coupled to an optical cavity which creates an absorption pathlength greater than 1000m. The experimental design allows optical feedback of infra-red light, resonant within the cavity, to the QCL, which initiates self-locking at each TEM00 cavity mode frequency excited. The QCL linewidth is narrowed to below the mode linewidth, greatly increasing the efficiency of injection of light into the cavity. At the frequency of each longitudinal cavity mode, the absorption coefficient of an intracavity sample is obtained from the transmission at the mode maximum, measured with a thermoelectrically cooled detector: spectral line profiles of CH4 and N2O in ambient air were recorded simultaneously and with a resolution of 0.01386cm−1. Aminimum detectable absorption coefficient of 5.5×10−8cm−1 was demonstrated after an averaging time of 1 s for this completely thermoelectrically cooled system. The bandwidth-normalised limit for a single cavity mode is 5.6×10−9cm−1 Hz−1/2 (1σ). Springer-Verlag, 2010 Hamilton D. School of Chemistry, University of Bristol, Cantock's Close, BS8 1TS, Bristol, UK aut Orr-Ewing A. School of Chemistry, University of Bristol, Cantock's Close, BS8 1TS, Bristol, UK aut Applied Physics B Springer-Verlag 102/4(2011-03-01), 879-890 0946-2171 102:4<879 2011 102 340 https://doi.org/10.1007/s00340-010-4259-4 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00340-010-4259-4 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hamilton D. School of Chemistry, University of Bristol, Cantock's Close, BS8 1TS, Bristol, UK aut NATIONALLICENCE 700 1- Orr-Ewing A. School of Chemistry, University of Bristol, Cantock's Close, BS8 1TS, Bristol, UK aut NATIONALLICENCE 773 0- Applied Physics B Springer-Verlag 102/4(2011-03-01), 879-890 0946-2171 102:4<879 2011 102 340 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer