THE INFRARED AND RAMAN-SPECTRUM OF DICYANOACETYLENE - THE UPSILON-FUNDAMENTAL

The Raman spectrum of liquid dicyanoacetylene, NC-C=C-CN, was reinvest igated and nu3 found at 617 cm-1. The Fermi resonance between nu1 and 2nu5 is explained, considering the isotopic species NC-C-13-C-CN. The high resolution infrared spectrum of the lowest frequency fundamental nu9 has been recorded for the first time, and the rotational constants for several states with v9 less-than-or-equal-to 9 have been determin ed.