Absolute line intensity with FT-ICLAS: 12C2H2 near 12 800 cm−1

We have used a Fourier transform intracavity laser absorption spectrometer to measure the absolute intensity of lines in the ν1 + 3ν3 band of 12C2H2 at 12675 cm−1. Under optimal conditions the agreement is found to be within 5% of reference values measured by conventional Fourier transform spectroscopy [F. Herregodts et al., Mol. Phys., 101 (2003) 3427]. The absolute intensity of 21 weaker lines not experimentally investigated in the latter work, is listed. Various tests of the instrumental method are presented, also demonstrating its ability to determine pressure self-broadening coefficients.