Six vibration-rotation bands of DCN between 2 and 6 µ have been analyzed. All the rotational constants have been obtained through the terms quadratic in vibrational quantum numbers. Two quadratic and seven cubic vibrational anharmonic constants have been obtained explicitly. Seven combinations of quadratic and cubic vibrational constants have also been obtained. Data are given on the analysis of the two parallel fundamental bands of D<sup>13</sup>CN, as well as the υ<sub>3</sub> bands of DC<sup>15</sup>N, H<sup>13</sup>CN, and HC<sup>15</sup>N. Δ-Δ transitions of both DCN and HCN in the υ<sub>3</sub> fundamental regions have been analyzed. The splitting of the Δ levels was clearly observed for the first time and is in agreement with the <i>l</i>-type resonance calculations. The line structure of the <i>Q</i> branches of both II-II and Δ-Δ “hot bands” has also been resolved. By means of the Ritz principle the levels 2υ<sub>2</sub><sup>0</sup>, 2υ<sub>2</sub><sup>2</sup>, and <sub>2</sub><sup>1</sup> of DCN and 2υ<sub>2</sub><sup>2</sup> of HCN have been determined.
ARTHUR G. MAKI, EARLE K. PLYLER, and ROBERT THIBAULT, "Vibration-Rotation Bands of Deuterium Cyanide and Hydrogen Cyanide," J. Opt. Soc. Am. 54, 869-875 (1964)