High resolution ZrF4-fiber-delivered multi-species infrared spectroscopy

Abstract

Using coherent broadband mid-infrared light from a picosecond optical parametric oscillator we introduce a flexible, easy to use, high-resolution technique which can be utilized to conduct remote stand-off, or fiber delivered, multi-species spectroscopy in a spectroscopically cluttered environment. In particular, both narrow line-like and broad continuum-like species can be handled simultaneously. If only species with narrow line-like absorptions are present, this can be done without the need for an explicit reference spectrum. We demonstrate the approach by performing absorption spectroscopy of H2O, CH4, CH3OH and C2H7NO (MEA) at high optical resolution (≈0.033 cm−1) and via fiber delivery, opening the possibility of conducting multi-species spectroscopy in remote and hazardous environments. Spectral co-fitting of all absorption features and of the spectrum of the light-source provides a robust means of determining species concentrations, with detection limits of 290 ppb and 890 ppb obtained for CH4 and MEA respectively using a 10.5-m Herriott cell and 32 seconds measurement time.