Resumen de High-resolution infrared and millimeterwave spectra of the v 3 =1 vibrational state of 14 NF 3 at 907 cm
H. Najib, N. Ben Sari-Zizi, J. Demaison, B. Bakri, J.-M. Colmont, E.B. MKadmi
The ν3±1 perpendicular band of 14NF3 ( cm−1) has been studied with a resolution of 2.5 × 10−3 cm−1, and 3682 infrared (IR) transitions (Jmax=55, Kmax=45) have been assigned. These transitions were complemented by 183 millimeterwave (MMW) rotational lines (Jmax=25, Kmax=19) in the 150–550 GHz region (precision 50–100 kHz). The kl=+1 level reveals a strong A1/A2 splitting due to the l(2,2) rotational interaction (q=−4.05 × 10−3 cm−1) while the kl=−2 and +4 levels exhibit small A1/A2 splittings due to l(2,−4) and l(0,6) rotational interactions. All these splittings were observed by both experimental methods. Assuming the v3=1 vibrational state as isolated, a Hamiltonian model of interactions in the D reduction, with l(2,−1) rotational interaction (r=−1.96 × 10−4 cm−1) added, accounted for the observations. A set of 26 molecular constants reproduced the IR observations with σIR=0.175 × 10−3 cm−1 and the MMW data with σMMW=134 kHz. The Q reduction was also performed and found of comparable quality while the QD reduction behaved poorly. This may be explained by a predicted Coriolis interaction between v3=1 and v1=1 (A1, 1032.001 cm−1) which induces a slow convergence of the Hamiltonian in the QD reduction but has no major influence on the other reductions. The experimental equilibrium structure could be calculated as: re(N–F)=1.3676 Å and ∠(FNF)=101.84°.
