Determination of line strengths by Fourier-transform spectroscopy

Abstract

A rigorous test of the photometric accuracy of commercial high-resolution Fourier transform spectrometers has been made by measuring line strengths in the pure rotational spectrum of carbon monoxide. Measurements have been made with a Bruker IPS 120 HR spectrometer (transitions: J″ = 7 . . . 23) and a Bomen DA3.002 spectrometer (J″ = 27 . . . 35). A least-squares fit of individual data sets and the combined data gave permanent electric dipole moments in the range 0.1091-0.1101 D and quadratic Herman-Wallis factors in the range -0.188 to -0.229 × 10(-3), in good agreement with literature values within the overall uncertainty. Sources of systematic errors in the Fourier-transform spectrometer and in the algorithms used to reduce the data are discussed in detail. The experimental results show that such errors affected the retrieved line strengths by less than 1%.