15min:

A. EL HILALI, L. H. COUDERT, LISA, CNRS/Universités Paris Est et Paris Diderot, 61 Avenue du Général de Gaulle, 94010 Créteil, France; AND S. KLEE, Physikalisch-Chemisches Institut, Justus-Liebig-Universität Gieß en, 35392 Gieß en, Germany.

Contrary to the isotopic specie of methanol with a symmetrical CH₃ or CD₃ methyl group, in the mono-deuterated species CH₂DOH the hindering potential no longer displays 3-fold symmetry and all moments of inertia depend on the angle of internal rotation. For this reason, this mono-deuterated species displays a fairly dense torsional spectrum difficult to compute and to assign.

In this paper an analysis of the torsional spectrum of mono-deuterated methanol is presented. More than 40 torsional subbands have been assigned in the 20 to 800~cm^-1 region. The body of data available for CH₂DOH consists of these newly assigned subbands and of the already available ones. The observed torsional subbands are characterized by K \leq 10 and v_t \leq 10. For 23 subbands, the rotational structure could be analyzed and this provides us with a mean to check their torsional assignment. The positions of the subband centers were analyzed with a theoretical approach accounting for the dependence of the inertia tensor on the angle of internal rotation. This allowed us to reproduce 58 experimental wavenumbers with an RMS value of 0.12~cm^-1. The spectroscopic parameters corresponding to the hindering potential and to the inertia tensor were also retrieved.