%0 Journal Article %A Ilyushin, V. V. %D 2012 %I Begell House %K Rho axis method, hindered internal rotation, microwave spectroscopy, torsion-rotation spectrum %N 2 %P 159-167 %R 10.1615/RadioPhysicsRadioAstronomy.v3.i2.80 %T MICROWAVE SPECTROSCOPY OF TORSION VIBRATIONS IN MOLECULES: APPROXIMATION OF STRICT COUPLING BETWEEN THE STRUCTURAL TORSIONAL PARAMETERS ρ AND F IN THE RHO AXIS METHOD %U https://www.dl.begellhouse.com/journals/6fd1549c0e2c05da,6f536281699b948c,6d1ac1e73424c362.html %V 3 %X In the paper, the approximation of strict coupling between the structural torsional parameters F and ρ in the Rho axis method and its applicability to analyzing the observed molecular spectra are considered for the molecules with methyl top hindered internal rotation. The functional relation between the F and ρ parameters which is implied in the rigid molecular structure approximation makes it possible to replace variation of these two parameters by variation of a single structural parameter, namely, of the moment of inertia of the C group which is in torsion motion. The approximation in question has been verified through processing spectrum measurement data for a number of molecules which spectra have been analyzed in the literature using standard Rho axis method. It is shown that structural distortions in molecules with hindered internal rotation of the C group, which are associated in the standard model of the Rho axis method with separate variation of the F and ρ parameters, are insignificant for the ground torsional state and can be accounted for through considering the fourth-order terms of the Hamiltonian in the course of fitting the spectra of excited torsional states. %8 2012-05-15