Synchrotron-Based High Resolution Far-Infrared Spectroscopy of <i>trans</i>-Butadiene
Marie‐Aline Martin‐Drumel, Jessica P. Porterfield, Manuel Goubet, Pierre Asselin, Robert Georges, P. Soulard, Matthew Nava, P. Bryan Changala, Brant Billinghurst, Olivier Pirali, Michael McCarthy, Joshua H. Baraban
Abstract
The high resolution far-infrared spectrum of trans -butadiene has been reinvestigated by Fourier-transform spectroscopy at two synchrotron radiation facilities, SOLEIL and the Canadian Light Source, at temperatures ranging from 50 to 340 K. Beyond the well-studied bands, two new fundamental bands lying below 1100 cm –1, ν 10 and ν 24, have been assigned using a combination of cross-correlation (ASAP software) and Loomis-Wood type (LWWa software) diagrams. While the ν 24 analysis was rather straightforward, ν 10 exhibits obvious signs of a strong perturbation, presumably owing to interaction with the dark ν 9 + ν 12 state. Effective rotational constants have been derived for both the v 10 = 1 and v 24 = 1 states. Since only one weak, infrared active fundamental band (ν 23 ) of trans -butadiene remains to be observed at high resolution in the far-infrared, searches for the elusive gauche conformer can now be undertaken with considerably greater confidence in the dense ro-vibrational spectrum of the trans form.