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

Abstract

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, D J = 9.2651 (18) kHz, D JK = -16.3922(18) kHz, H J , = -8.8(34) • 10 -3 Hz, H JK = -15.8(73) • 10 -3 Hz, and H KJ = 34.2(73) • 10 -3 Hz. An r 0 - and an r e -structure are presented: r 0 = 1.4198(7) Å (calculated from B), r 0 = 1.4210(7) Å (calculated from C), and r e = 1.4175 Å