High-resolution spectrum of the 3 nu(1) band of cyanoacetylene obtained via infrared/infrared double resonance

The 3v(1) band of cyanoacetylene has been recorded with 0.0005 cm(-1) resolution using sequential infrared/infrared double resonance excitation. Rotational levels from 0 less than or equal to J' less than or equal to 6 were measured and used to calculate v(0), B', and D'(J). The spectrum is slightly perturbed, with its features showing fractionation into two or three lines due to the onset of intramolecular vibrational energy redistribution. (C) 1996 Academic Press, Inc.