THE HIGH-RESOLUTION INFRARED-SPECTRUM OF CYANOBUTADIYNE, HC5N - THE NU(7) BAND CENTERED AT 642 CM(-1)

The upsilon(7) infrared band of cyanobutadiyne (HC5N) was recorded for the first time with high resolution by FTIR spectroscopy using a samp le produced by gas electric discharge. The fundamental band and the ho t bands arising from the upsilon(11) = 1 and 2 states are identified. The molecular parameters, including the rotational and vibrational l-t ype doubling constants, have been determined accurately by analyzing t he spectra together with the available microwave and millimetre wave d ata. The intensity perturbation caused by the l-type resonance in the (upsilon(7), upsilon(11))=(1,1) state has been clearly observed and di scussed.