Frequency-comb-assisted absolute calibration and linestrength of H12C13CH ro-vibrational transitions in the 2?3 band

We report on a precision spectroscopic study of room-temperature HCCH in the 6463-6520 cm-1 range, using a continuous-wave diode laser phase-locked to a near-infrared optical frequency comb synthesizer stabilized, in turn, against a GPS-disciplined rubidium clock. By tuning the comb repetition frequency, several ro-vibrational transitions in the P and R branches of the 2? overtone band are recorded. Accuracy levels as low as 100 kHz, 5·10 in fractional terms, are obtained in the determination of absolute line-center frequencies. In addition, line intensities are measured for the first time, with a best fractional uncertainty of 1%, and used to retrieve the purely vibrational transition dipole moment in conjunction with the first-order Herman-Wallis factor. Finally, the pressure broadening coefficients ? are also derived for the studied transitions.