15min:

L. MARGULÈS, J. DEMAISON, Laboratoire PhLAM, CNRS UMR 8523, Université de Lille 1, Bat. P5, 59655 Villeneuve d'Ascq Cedex, France.; A. PERRIN, Laboratoire Inter Universitaire des Systemes Atmosphériques, CNRS UMR 7583, Université Paris 12, 61 Av du General de Gaulle, 94010 Créteil Cedex France.; I. MERKE, ; Institute für Physikalische Chemie, RWTH Aachen, 52056 Aachen, Germany; H. WILLNER, Anorganische Chemie, FB C, Universität-GH Wuppertal, 42097 Wuppertal, Germany; M. ROTGER, Groupe de SpectromŽtrie Moléculaire et AtmosphŽrique, CNRS UMR 6089, Moulin de la Housse, BP 1039, Cases 16-17, 51687 Reims Cedex 2, France; AND V. BOUDON, Institut Carnot de Bourgogne, UMR CNRS 5209, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France.

The ground state rotational spectrum of the near-spherical top molecule S¹⁸O₂F₂ (sulfuryl fluoride) has been measured from 50 to 700 GHz. As for the parent isotopologue, S¹⁶O₂F₂\footnote[1] K. ~Sarka, J.~Demaison, L.~Margulès, I.~Merke, N.~Heineking, H.~Bürger, and H.~Ruland, J. Mol. Spectrosc. , \textbf200, 55 (2000), it was necessary to use a non-reduced Hamiltonian in order to obtain a satisfactory fit. It was possible to determine six quartic centrifugal distortion constants (instead of five for a standard asymmetric top) and an additional sextic constant could also be determined. This ground state level has also been analysed thanks to a tensorial formalism developed in Dijon. Only two tensorial sextic constants are fixed to zero, all others have been adjusted. Although S¹⁸O₂F₂ is less spherical than S¹⁶O₂F₂, the analysis was more difficult. It is partly due to the fact that S¹⁸O₂F₂ is oblate whereas S¹⁶O₂F₂ is prolate. The experimental quartic centrifugal distortion constants were found in good agreement with those calculated from the force field, confirming the correctness of the analysis.