SIMBAD references

Two hundred and fifty-one ¹²C₂D₂ transitions have been measured in the 0.2-1.6 THz region of its ν₅-ν₄ difference band and 202 of them were observed for the first time. The accuracy of these measurements is estimated to be ranging from 50 kHz to 100 kHz. The ¹²C₂D₂molecules were generated under room temperature by passing 120-150 mTorr D₂ O vapor through calcium carbide (CaC₂) powder. A multistate analysis was carried out for the bending vibrational modes ν₄ and ν₅of ¹²C₂D₂, which includes the lines observed in this work and prior microwave, far-infrared and infrared data on the pure bending levels. Significantly improved molecular parameters were obtained for ¹²C₂D₂ by adding the new measurements to the old data set, which had only 10 lines with microwave measurement precision. New frequency and intensity predictions have been made based on the obtained molecular parameters. The more precise measurements and new predictions reported here will support the analyses of astronomical observations by the future high-resolution spectroscopy telescopes such as Herschel, SOFIA, and ALMA, which will work in the terahertz spectral region.