The Forbidden RotationalQ-Branch of CH3CF3: Torsional Properties and (A1−A2) Splittings

Infrared and Millimeter-Wave Study of the Four Lowest Torsional States of CH3CF3

“…By using the form of the zeroth-order torsion-rotation Hamiltonian given in Eq. [3], the Hamiltonian matrix for H T 0 in the PAM basis functions ͉J, k, ; k f ͘ has exactly the same form as that for a IAM Hamiltonian in a IAM basis. This occurs because, for a symmetric top, rotation about the symmetry axis does not affect the moment-of-inertia tensor.…”

“…A torsion-rotation contact transformation has been used to eliminate terms like J ␣ 2 (1 Ϫ cos 3␣)/2 (4, 13). Finally, a rotational contact transformation has been used to simplify H S (3). In an effort to simplify the notation, no attempt has been made to distinguish the transformed and untransformed Hamiltonian operators.…”

“…Much of the theoretical framework for the analysis of the current data set has been developed in earlier studies of CH 3 SiH 3 (4,8,9) and CH 3 CF 3 (3). While the current data set can be analyzed without any substantive changes in the older methods, the later analyses of the vibrational fundamentals will require several significant modifications in the formalism used.…”

“…In the current work, a third method has been applied to the measurement of the torsional energies in CH 3 CF 3 . The torsional overtone (v 6 ϭ 2 4 0) has been studied at a resolution of 0.005 cm Ϫ1 using Fourier transform spectroscopy.…”

“…The avoided-crossing molecular beam method has been used to determine the -splittings for CH 3 CF 3 in the ground torsional state (1,2). More recently, distortion moment microwave spectroscopy has been used to measure the -splittings for CH 3 CF 3 for the ground and first excited torsional states (3).…”