Band systems of dicyanoacetylene involving ν 7

Abstract High resolution infrared spectra of several hot band systems of NC–C C–CN involving ν 4 , ν 5 , ν 7 , ν 8 , and ν 9 have been investigated. A strong Fermi resonance between ν 3 and 2 ν 7 (l=0) as well as between combination levels of these has been identified. Eighteen line series have been analyzed and effective rotational constants have been determined.