The rotational spectrum of ND. Isotopic-independent Dunham-type analysis of the imidogen radical.

The rotational spectrum of 15ND in its ground electronic X3Σ- state has been observed for the first time. Forty-three hyperfine-structure components belonging to the ground and ν = 1 vibrational states have been recorded with a frequency-modulation millimeter-/submillimeter-wave spectrometer. These new measurements, together with the ones available for the other isotopologues NH, ND, and 15NH, have been simultaneously analysed using the Dunham model to represent the ro-vibrational, fine, and hyperfine energy contributions.

The spectroscopic analysis of the v₂=1, v₅=1, and v₃=v₆=1 infrared vibration system of H₃SiI.

The ν2 (A1)/ν5 (E)/ν3+ν6 (E) band system of H3(28)SiI was investigated using Fourier transform infrared spectra recorded from 820 to 1100 cm(-1) at a resolution of 2.0×10(-3) cm(-1). In total, 11,903 transitions were assigned.

The experimental equilibrium structure of acetylene.

The empirical equilibrium structure of acetylene has been derived by exploiting the very precise experimental rotational constants available in the literature for the 10 isotopologues relative to all the possible combinations of H, D, (12)C and (13)C atoms. The geometry obtained when data for all species are fitted together is: re(CH) = 106.167(14) pm and re(CC) = 120.

The infrared spectrum of (12)C2D2: the stretching-bending band system up to 5500 cm(-1).

The infrared spectrum of the perdeuterated acetylene, (12)C2D2, has been recorded from 900 cm(-1) to 5500 cm(-1) by Fourier transform spectroscopy at a resolution ranging between 0.004 and 0.009 cm(-1).

The anharmonic force field of 1,3-cyclopentadienes.

The cubic and quartic semi-diagonal anharmonic force fields of 1,3-cyclopentadienes, C(5)H(6) and C(5)D(6), of the 1,3-cyclopentadiene-5-d and 1,3-cyclopentadiene-1,2,3,4,5-d(5) have been obtained using density functional theory, DFT, with the B97-1 functional and a triple-zeta plus double polarization (TZ2P) basis set. The 108 fundamental frequencies computed by second order vibrational perturbation theory are in very good agreement with the experimental data, with a root mean square deviation (RMSD) equal to 7 cm(-1). Some fundamental frequencies have been reassigned and two have been assigned for the first time on the basis of the present results.

Ab initio anharmonic force field and rotational analyses of infrared bands of perchloryl fluoride.

Perchloryl fluoride, FClO(3), has been studied both experimentally and theoretically, using high-resolution Fourier transform spectroscopy and high-level ab initio methods. The geometry, dipole moment, and anharmonic force field of the molecule have been calculated ab initio, using the coupled-cluster with single, double, and perturbative triple excitations [CCSD(T)] level of theory. The infrared spectra of monoisotopic species have been recorded.

Anharmonic force fields of naphthalene-h8 and naphthalene-d8.

The cubic and the quartic semidiagonal anharmonic force fields of naphthalene-h8 and -d8 are obtained using density functional theory (DFT) with the B9-71 functional and a triple-zeta plus double polarization (TZ2P) basis set. The fundamental frequencies computed by second-order vibrational perturbation theory are in very good agreement with the experimental data, with a mean absolute deviation (MAD) of 4 cm(-1) for C(10)H(8) and 6 cm(-1) for C(10)D(8). Some of the fundamental frequencies have been reassigned on the basis of the present results.