Thirty bands of C<sub>2</sub>D<sub>2</sub> have been observed and measured between 1900 and 3300 cm<sup>-1</sup>. Twenty of these have been resolved well enough to permit extraction of rotational constants. The Δ<sub>2</sub><i>F</i> values up to <i>J</i>35 for three Σ<sub><i>g</i></sub> ground state bands were averaged and correlated with other data for a more reliable <i>B</i><sup>0</sup>=0.84794 ±0.00005 and <i>D</i><sup>0</sup>=7.85×10<sup>-7</sup>±0.4×10<sup>-7</sup>, where the indicated uncertainties are the probable errors of the coefficients. Better resolution and higher <i>J</i> values have reduced the uncertainty derived from other sources. The <i>l</i>-type doubling constants for ν<sub>4</sub><sup>1</sup> and ν<sub>5</sub><sup>1</sup> have been obtained from resolved <i>Q</i> branches and split <i>P</i> and <i>R</i> branches; they are <i>q</i><sub>4</sub> =0.00316 and <i>q</i><sub>5</sub>=0.00314 cm<sup>-1</sup>.
EUGENE D. TIDWELL and EARLE K. PLYLER, "Infrared Spectrum of Dideuteroacetylene (C2D2)," J. Opt. Soc. Am. 52, 656-664 (1962)