V.A. Job

High resolution diode laser measurements on the ν2 bands of 14NH3 and 15NH31

Abstract More than 500 lines in the ν2 bands of 14NH3 and 15NH3 have been measured in the region 740–1200 cm−1 with a diode laser spectrometer, with an accuracy better than 0.0005 cm−1 for most of the lines. Wavenumbers (in cm−1) were determined using a 3-in. Ge etalon for calibration and OCS, N2O, NH3, and CO2 lines as references. The diode laser data were combined with pure inversion and inversion rotation frequencies and sets of rotational constants were obtained by the method of merged least squares. Perturbations between the Δk = ±3 levels have been taken into account in these calculations.

Transition dipole moments and refined molecular parameters for the ν2 band of ND2H

Abstract More than 100 new lines in the ν 2 band of ND 2 H have been measured by diode laser spectroscopy. The parameters of ND 2 H in the ground and ν 2 states have been refined by the simultaneous analysis of microwave, FTIR, and diode laser data. The intensities of several lines were quantitatively measured and from these the transition dipole moments were determined. The calculated wave-numbers and intensities of the stronger lines in the ν 2 band of ND 2 H are listed.

Inversion-rotation interaction in NH2D: Intensity perturbations in the ν2 band

The parameters of NH 2 D in the ground and ν 2 states have been refined by a simultaneous analysis of the microwave, FTIR, and diode laser data. The intensities of 46 NH 2 D lines have been measured, and from a least-squares fit of the intensity data the a ← s, s ← a, s ← s, and a ← a transition moments have been derived. The intensities of the lines in the ν 2 band of NH 2 D have been calculated taking into account the inversion-rotation interaction. The accuracies of the wavenumbers and intensities calculated with the new parameters are estimated to be better than ±0.0002 cm -1 and ±5%, respectively. The matrix elements for interaction of vibrations through x, y, and z axis couplings are appended.

Rotational analysis of the ν2 band of NH2D

High-resolution diode laser spectra and medium-resolution F-T spectra of deuterated ammonia have been obtained in the 700- to 1030-cm -1 region. Out of about 800 lines measured by diode laser spectroscopy, approximately 500 lines have been assigned to the ν 2 transitions of NH 2 D. The parameters for the ground and ν 2 states of NH 2 D have been derived by the simultaneous analysis of the infrared and microwave data. The standard deviation for the IR data is ~8 × 10 -4 cm -1 . It is shown that the energy levels of NH 2 D in the ν 2 state are heavily perturbed by inversion-rotation interaction and that it is necessary to include higher order inversion-rotation interaction terms to obtain a satisfactory fit of the observed data.

Diode laser spectrum and analysis of the 882-cm−1 band of s-tetrazine

Abstract A high-resolution diode laser spectrum of the 882-cm−1 band of s-tetrazine has been obtained. A complete rotational analysis of this band, incorporating quartic and sextic centrifugal distortion coefficients, has been carried out. The rotational constants A, B, and C have been determined with an accuracy better than 10−5 cm−1. The analysis has shown the band to be A-type and, on this basis, the vibrational assignment of this band has been revised from ν12 to ν14.

Intensities of lines in the bands ν2 and ν4 and the transition dipole moments of PH3

Abstract The absolute intensities of 57 vibration-rotational spectral lines of transitions to the vibrational states v 2 = 1 and v 4 = 1 of PH 3 have been measured with a diode laser. With account being taken of the mixing of the wavefunctions of both vibrational states, the values of the vibrational transition moments and their relative signs were determined by a least-squares fit to the experimental data: 〈0, 0 0 ∥ μ z ∥1, 0 0 〉 = (0.23913 ± 0.00093) × 10 −30 C m and 〈0, 0 0 ∥ μ x ∥0, 1 ±1 〉 = −(0.14060 ± 0.00137) × 10 −30 C m.

High-resolution diode laser spectra of the ν4 mode of 12CF3I and 13CF3I

Abstract High-resolution spectra of the ν 4 mode of 12 CF 3 I and 13 CF 3 I have been recorded using diode laser spectroscopic techniques. The sample was cooled to 163 ± 10 K to suppress the hot bands. Natural CF 3 I containing 98.9% 12 CF 3 I and 1.1% 13 CF 3 I was used for recording the spectra. About 1200 lines in the P and R branches of each isotopic molecule have been assigned and used in the least-squares fit. The pseudoparallel structure of the bands has been understood and accurate values of rotational constants have been obtained.