The direct l-type resonance spectrum of CF3CCH in the vibrational state v10=3:: Extension of the theory of reduction to H6n terms

The direct 1-type resonance spectrum of CF3CCH has been measured in the v(10) = 3 vibrational state by means of waveguide microwave Fourier transform spectroscopy in the range 8-26 GHz. Three types of direct 1-type resonance transitions induced by the (Delta k = Delta l = 2) interaction could be observed: 140 transitions following the Delta J=O, Delta k=Delta l= 2, Delta vertical bar 1 vertical bar =0, selection rule covering values of J= 17-61 and G= vertical bar k-1 vertical bar from 1 to 7, 94 transitions following the Delta J=0, Delta k=Delta l= +/- 2, A vertical bar 1 vertical bar = 2, selectionrule covering values of J=26-57 and G from 15 to 24, 90 transitions following the Delta J=O, Delta k=Delta l= 4 selection rule covering values of J=34-80 and G from 3 to 12 and 13 transitions following the Delta J=O, Delta k=Delta l= 6, k= +/- 1, 1= +/- 1 double left right arrow k= +/- 5, 1 = +/- 3 selection rule for J=71-83. 14 A(1)-A(2) splitting transitions with kl = +1 were measured from J= 33 to 49. Strong perturbations due to Delta(k - 1) = 3 interactions made possible the observation of perturbation-allowed transitions with selection rule k = +/- 4, 1 = +/- 3 double left right arrow k = +/- 3, 1 = +/- 1. Furthermore, the rotational transitions J = 2-1, 3-2 and 4-3 have been measured. To make use of the multiple fitting concept, the theory of reduction developed for the v(1) = 2 vibrational state by Sarka and Harder [K. Sarka, H. Harder, J. Mol. Spectrosc. 197 (1999) 2541 has been extended to the v(t) = 3 vibrational state including terms up to H-62. Owing to problems in the reproduction of data with low K and A(1)-A(2) symmetry, two types of fits have been performed using five reduced forms of the effective Hamiltonian. The first type of fit used a reduced data set for which part of the transitions has been omitted. The unitary equivalence of the determined parameter sets has been demonstrated including newly derived relations for parameters in v(10) = 3. In the second type of fit, the complete data set has been included, yielding satisfactory results only in one reduction. In both type of fits, parameters up to sixth order have been determined including the axial rotational constant A and the Coriolis constant A for both values of 1. General features of the direct 1-type resonance spectrum in a vt = 3 level are discussed. (c) 2005 Elsevier B.V. All rights reserved.