The Centrifugally Induced Pure Rotational Spectrum and the Structure of Sulfur Trioxide. A Microwave Foúrier Transform Study of a Nonpolar Molecule

Abstract

The pure rotational spectrum of sulfur trioxide has been observed for the first time. A total of 25 high-J transitions could be assigned. The rotational constants, two quartic centrifugal distortion constants, and three sextic centrifugal distortion constants were determined as: B= 10 449.0667(23) MHz, C = 5216.0330(12) MHz, Dj = 9.2651 (18) kHz, DJK= — 16.3922(18) kHz, HJ = −8.8(34) • 10-3 Hz, HJK = —15.8 (73) • 10-3 Hz, and HKJ= 34.2 (13)• 10-3 Hz. An ro− and an re-structure are presented: ro= 1.4198(7) Å (calculated from B), ro= 1.4210(7) Å (calculated from C), and re= 1.4175 Å. © 1991, Walter de Gruyter. All rights reserved.