The high resolution far-infrared sPectrum of transbutadiene has been reinvestigated by Fourier-transform spectroscopy rtoil c PY at two synchrotron radiafi n facilities,. g LEs11-0 tooan340 K.Canadian Light Source,. at temPeratures ranging from Beyond the well -studied bands, two new fundamental bands, lyinga below 1100 cm 1, filo and 1'24, have been assigned,,,usiningis_ combination of cross -correlation (ASAP software) and 1,00 Tyvood type (LWWa software)rather straightforward,xh.b'ts obvious signsofdiagrams. While the v24 analysis was esumab interaction thedark +av9strong perturbation, pr state. Effective rotational constants have been derived for bofh the vlo= 1 and v24 = 1 states. Since only one weak, infrared active fundamental band ( of trans butadiene remains to be observed at high resolution in the gauche conformer can now be undertaken with consIderablY greater confidence in the dense form.