The v(4)=1 state of (NF3)-N-14 at 493 cm(-1) studied by high-resolution FTIR, centimeter-wave, and miliimeter-wave spectroscopy

摘要

The nu(4) band of NF3, (ν) over bar (0) = 493.423 cm(-1), has been studied by FTIR spectroscopy with a resolution of 3 x 10(-3) cm(-1). Strong intensity perturbation by C(2, 2) resonance is revealed. The more than 5000 IR assignments were complemented by 132 millimeter-wave measurements in the regions 140-250 and 340-470 GHz, by 7 new or formerly reported J = 1-0 and 3-2 microwave frequencies, and by 134 DeltaJ = 0, Deltak = Deltal = 2 direct C-type centimeter-wave transitions in the region 826 GHz with J(max) = 22 and 15, The rotational data enabled detection of splittings caused by C(2, -4) (t) and (0, 6) (h(3)) interactions in excess to those by l(2, 2) (q) effects. The A(1)A(2) splitting of the kl = -2 level was not detected on the DeltaK = -1 IR transitions owing to their vanishing intensity for J > 18. In contrast, A(1)A(2) doublets were observed in transitions with 28 less than or equal to J less than or equal to 43 reaching the kl = +4 level. All appropriately weighted observations were fitted together to 28 free parameters up to sextic terms employing three different (D, Q, QD) reductions of the rovibrational Hamiltonian, and the equivalence of the reductions was established. The sets of molecular constants obtained from the merged data reproduce the IR observations with or = 0.24 x 10(-3) cm(-1), the millimeter-wave data with sigma = 29 kHz, and the centimeter-wave measurements with sigma = 3 kHz. (C) 2002 Elsevier Science (USA). [References: 35]