@inproceedings{f5def7b5bac94423952229851d62573b,
title = "Using quantum cascade lasers with resonant optical cavities as a diagnostic tool",
abstract = "Absorption spectroscopy based on optical resonators is known to be a very sensitive diagnostic technique. For many years the infrared spectral range could not be employed, because of the lack of suitable radiation sources with the required power and tunability. Recent advances in semiconductor laser technology, in particular the advent of quantum cascade lasers (QCL) provides new possibilities for highly sensitive and selective detection of molecular species. Cavity Enhanced Absorption Spectroscopy (CEAS) with a thermoelectrically (TE) cooled cw QCL emitting at 7.66 µm and employing a ~0.5 m long cavity yielded effective path lengths of 1080 m and a sensitivity of 2 x 10-7 cm-1 Hz-1/2, mainly limited by incomplete averaging over cavity resonances. The molecular concentration detection limit with a 20 s integration time was found to be 6 x 108 molecules/cm3 for N2O and 2 x 10 9 molecules/cm3 for CH4 which is good enough for the selective measurement of trace atmospheric constituents at 2.2 mbar. {\textcopyright} 2009 IOP Publishing Ltd",
author = "S. Welzel and G. Lombardi and P.B. Davies and R.A.H. Engeln and D.C. Schram and J. R{\"o}pcke",
year = "2009",
doi = "10.1088/1742-6596/157/1/012009",
language = "English",
series = "Journal of Physics: Conference Series",
publisher = "Institute of Physics",
pages = "012009--1/8",
editor = "P.B. Davies and J. R{\"o}pcke and F. Hempel",
booktitle = "Proceedings of the 3rd International Workshop on Infrared Plasma Spectroscopy, 23–25 July 2008, Greifswald, Germany",
address = "United Kingdom",
}