INTERNAL AXIS MOLECULAR-PARAMETERS, TORSIONAL ENERGIES AND MATRIX-ELEMENTS OF METHYL MERCAPTAN-D-1

In this paper an internal axis method Hamiltonian model has been appli ed to evaluate the torsional-rotational molecular parameters of asymme trically substituted methyl mercaptan (CH2DSH) using previously observ ed microwave transitions. The torsional barrier potential barrier func tions V-1, V-2 and V-3 have been refined. The observed microwave trans ition frequencies have also been fitted to an energy expansion model, which allowed accurate predictions of yet unobserved transition freque ncies with microwave accuracy. These values are independent of the Ham iltonian model used and will prove valuable for astrophysical detectio n. The matrix elements between various torsional sub-levels upto the f ourth excited torsional state in the ground vibrational state. (C) 199 7 Elsevier Science B.V.