Thirty bands of C2D2 have been observed and measured between 1900 and 3300 cm-1. Twenty of these have been resolved well enough to permit extraction of rotational constants. The Δ2F values up to J35 for three Σg ground state bands were averaged and correlated with other data for a more reliable B0=0.84794 ±0.00005 and D0=7.85×10-7±0.4×10-7, where the indicated uncertainties are the probable errors of the coefficients. Better resolution and higher J values have reduced the uncertainty derived from other sources. The l-type doubling constants for ν41 and ν51 have been obtained from resolved Q branches and split P and R branches; they are q4 =0.00316 and q5=0.00314 cm-1.
EUGENE D. TIDWELL and EARLE K. PLYLER, "Infrared Spectrum of Dideuteroacetylene (C2D2)," J. Opt. Soc. Am. 52, 656-664 (1962)