THE FUNDAMENTAL VIBRATIONS OF NC-CC-CN (DICYANOACETYLENE)

Abstract In the infrared spectrum of dicyanoacetylene the rotation vibration bands ν 1 − ν 9 /2ν 5 − ν 9 , ν 1 + ν 9 /2ν 5 + ν 9 (Fermi resonance), ν 2 − ν 9 , ν 2 + ν 8 , ν 4 , ν 6 − ν 9 , ν 6 + ν 8 − ν 6 , ν 4 − ν 7 , ν 4 + ν 7 , ν 4 + ν 7 − ν 7 , ν 7 + ν 8 − ν 7 , and 2ν 7 + ν 8 − ν 7 (I and II) have been recorded with high resolution. From these bands the vibrational levels v 1 = 1, v 2 = 1, v 4 = 1, v 6 = 1, and v 7 = 1 including the corresponding effective rotational constants have been calculated. Different methods for calculating the unperturbed position of the v 1 = 1 level have been compared and the unperturbed B 1 has been calculated. Additional information on the rotational constants of v 8 = 1 and v 9 = 1 is also given.