Using FT spectra (Bruker IFS 120, unapodized FWHM resolution E 0.001 cm À1 ) of acetylene 12 C 2 H 2 , absolute positions and intensities have been measured for about 250 lines between 2600 and 2800 cm À1 in the n 2 þ n 1 5 and ð3n 4 þ n 5 Þ 0 þ cold bands, and in the n 1 À n 1 5 ; n 3 À n 1 4 ; and
These measurements improve the accuracy of wavenumbers previously available and lead to individual line intensities for the first time in this spectral region. A multispectrum fitting procedure has been used to retrieve line parameters from five experimental spectra recorded at different pressures. The frequencies of the n 3 band of 12 C 16 O 2 allowed to perform an absolute wavenumber calibration. The accuracy of the amount of 12 C 2 H 2 in the sample has been checked using the 3n 1 5 cold band around 2100 cm À1 , and has been estimated to be around 72%. The average absolute accuracy of the line parameters obtained in this work has then been estimated to be 70.0002 cm À1 for line positions, and 75% for line intensities. For each studied band, the vibrational transition dipole moment squared value has been determined, as also empirical Herman-Wallis coefficients. A complete line list containing positions and intensities for the five strongest bands around 3.8 mm has been set up for atmospheric applications.