High-resolution Fourier-transform intra-cavity laser absorption spectroscopy: application to 12C2H2 near 12 300 cm−1

The capabilities of intra-cavity laser absorption spectroscopy associated with a high-resolution Fourier-transform spectrometer (FT-ICLAS) are investigated with a Ti:Sapphire laser. Weak absorption lines of atmospheric water were used to test the accuracy of absolute intensity measurements by FT-ICLAS leading to an excellent agreement (a few %) with the HITRAN data. The performances in terms of spectral resolution (0.028 cm−1) and sensitivity (2×10−9 cm−1) are illustrated by the spectroscopic study of the overtone spectrum of 12C2H2 between 12 250 and 12 400 cm−1 which allowed for a significant improvement of recent cavity ring-down measurements. Among the three Π–Σ bands rotationally analyzed, one is newly observed. The absolute intensity values of the bands are given.