Analysis of rotational and rovibrational spectra of SiDF3 in the ground and upsilon(4)=1 excited states

This paper presents the analysis of the spectra of SiDF3 in its vibrational ground and v(4) = 1 states. The pure rotational spectrum of the ground sta te was measured up to 903 GHz (J(n) = 65). Rotational, quartic, and sextic centrifugal distortion constants were accurately determined. Furthermore th e parameter /h(3)/ = 7.64(11) x 10(-4) Hz was derived from the observation of A(1)-A(2) splittings of six K = 3 lines. The assignment of the v(4), = 1 spectrum was performed by combining 140 pure rotational frequencies and mo re than 2300 rovibrational transitions. Among them, because of the strong ( +/-2, +/-4) interaction, there are more than 90A(1)-A(2) resolved split tra nsitions between the (1 = 0, k = +/-3) ground state levels and the (1 = +/- 2, k = +/-1) v(4) = 1 levels. Although the v(4) band is located at about 99 4.3 cm(-1), the energies of the other fundamental bands are at a distance o f more than 140 cm(-1). The assumption of the isolated character of the sta te was confirmed by the small differences between the v(4), = 1 state and t he ground state parameters and by the possibility of using the D and Q redu ction schemes proposed by E. I. Lobodenko, O. N. Sulakshina, V. I. Perevalo v, and Vl. G. Tyuterev. (C) 1999 Academic Press.