Cavity enhanced FTIR spectroscopy using a femto OPO absorption source

Abstract

The ν₁ + ν₃ band of ¹²C₂H₂ was recorded using a high resolution continuous scan Fourier transform interferometer fitted with a femto OPO absorption source. Various experimental schemes were successfully implemented, including multipass absorption in a cell and also in a supersonic expansion, and cavity enhanced absorption. An optimal rms noise equivalent absorption of 2.2 × 10⁻⁹cm⁻¹Hz^−1/2 per spectral element was reached in the latter case, corresponding to α_min = 1.5 × 10⁻⁷cm⁻¹. Performances are illustrated and discussed.

Keywords:

• cavity enhanced absorption spectroscopy
• FTIR, femtosecond OPO comb spectroscopy
• femto-FT-CEAS

Acknowledgments

We are happy to dedicate this paper to Professor Di Lonardo, for his many contributions to the acetylene spectroscopy, a dedication shared with all of us. We thank B. Amyay and P. Van Poucke (ULB) for their help on various items. We are indebted to the ‘programme Currien/Tournesol’ collaboration sponsored by ‘Wallonie Bruxelles international’, F.R.S.-FNRS and ‘Région Wallone’, and ‘Ministère des Affaires étrangères’ and ‘Ministère de l’Education Nationale, de la Recherche et de la Technologie’ on the Belgian and French sides, respectively. This work was also sponsored in Belgium, by the Fonds National de la Recherche Scientifique (FNRS, contracts FRFC and IISN) and the ‘ Action de Recherches Concertées de la Communauté française de Belgique’.