THE NU-1 FUNDAMENTAL OF HCCN - EVIDENCE FOR QUASILINEARITY

The high resolution infrared spectrum of HCCN in the CH stretching reg ion has been observed by infrared kinetic spectroscopy, In addition to the CH stretching fundamental, upsilon1, several hot bands associated with the bending vibrations have been observed. By measuring the inte nsity of the band, upsilon1 + upsilon5 - upsilon5, relative to the fun damental, the energy of upsilon5 has been found to be 187 +/- 20 cm-1. This value is intermediate between that expected for a normal linear molecule and that expected for a bent molecule suggesting a very flopp y HCX bending potential that is characteristic of a quasilinear molecu le.