V.-M. Horneman

New wave-number calibration tables for H 2 O, CO 2 , and OCS lines between 500 and 900 cm −1

The pure rotational lines of H(2)O, the nu(2) band of CO(2), and the nu(1) band of OCS were simultaneously recorded by a Fourier transform spectrometer. The resolution achieved was ~0.0045 cm(-1), and the precision of the line position was typically 3.6 x 10(-5) cm(-1) or 1.2 MHz (standard deviation). The spectrum improves the accuracy of wave numbers of calibration lines in the region between 500 and 720 cm(-1) by a factor of ~10.

Analysis of highly excited ‘hot’ bands in the SO2 molecule: ν2 + 3ν3 − ν2 and 2ν1 + ν2 + ν3 − ν2

We set up a variational procedure of assignments of transitions and we applied it to the analysis very weak ‘hot’ bands, ν2 + 3ν3 − ν2 and 2ν1 + ν2 + ν3 − ν2, of the SO2 molecule. As the first step of the study, the ‘cold’ bands, 3ν3 and 2ν1 + ν3, are re-analysed and transitions belonging to those bands are assigned up to the values of quantum numbers J max. = 60, , and J max. = 69, for the bands 3ν3 and 2ν1 + ν3, respectively. After ‘cleaning’ the experimental spectrum from transitions belonging to the 3ν3 and 2ν1 + ν3 bands, a variational procedure was used that allowed us to assign 230 and 115 transitions with the values of quantum numbers J max. = 35, , and J max. = 26, for the bands ν2 + 3ν3 − ν2 and 2ν1 + ν2 + ν3 − ν2, respectively. The sets of spectroscopic parameters obtained by fitting the assigned experimental transitions reproduce the initial experimental data with an accuracy close to experimental uncertainties.

High-resolution rotational absorption spectra of H 2 16 O, HD 16 O, and D 2 16 O between 110 and 500 cm −1

Pure rotational spectra of 16O isotopic species of H2O, HDO, and D2O were measured with a high-resolution Fourier-transform spectrometer in order to obtain better calibration line positions for high-resolution spectroscopy. The number of assigned lines for HDO was ~380 and for H2O it was ~310 between 170 and 500 cm−1. For D2O, ~220 lines in the 110–420-cm−1 region were assigned. The calibration was performed with the highly accurate ν2 band of carbonyl sulfide.

Vibration-rotation bands of CO2 and OCS in the region 540–890 cm−1

Abstract The regions of the ν2 band of CO2 and the ν1 band of OCS have been simultaneously measured by the Fourier transform spectrometer (1, 2). The resolution achieved was now about 0.0045 cm−1. A total of eight “hot” bands of 12C16O2 and 16O12C32S and the fundamental bands ν2 of 13C16O2 and ν1 of 16O12C34S have been reported.

Vibration-rotation spectrum of N2O in the region of the lowest fundamental ν2

Abstract The high resolution infrared spectrum of N 2 O in the region of ν 2 has been studied with a Fourier transform spectrometer at a resolution of (about) 0.005 cm −1 and an accuracy of about ±0.00005 cm −1 . In addition to ν 2 , “hot” bands associated with this band and the bending fundamental ν 2 of 15 N 14 N 16 O and 14 N 15 N 16 O were analyzed.

Absolute OCS wavenumbers and analysis of bands in the region of the lowest fundamental ν2

Abstract The high-resolution infrared spectrum of carbonyl sulfide (OCS) in the region 490–560 cm −1 has been recorded with a Fourier transform spectrometer at a resolution of about 0.005 cm −1 . Measurements and analysis are given for the bands 01 1 0 ← 00 0 0, 02 2 0 ← 01 1 0, and 02 0 0 ← 01 1 0 of the 16 O 12 C 32 S isotopic species and for 01 1 0 ← 00 0 0 of the 16 O 12 C 34 S species.

Updating OCS 2ν2 band for calibration purposes

Abstract After our previous measurement of the OCS 2 ν 2 band, which was published by Tolonen et al. in J. Mol. Spectrosc. 144 , 18–26 (1990), a clear shift has been found in the OCS ν 1 band, which was our initial calibration source. Because the lines of the 2 ν 2 band are widely used for calibration purposes, we decided to remeasure the band by calibrating it directly with the highly accurate 9.4-μm band of CO 2 . The new center of the OCS 2 ν 2 band is 1047.042051 cm −1 with an accuracy of ±6 × 10 −6 cm −1 . This value is in perfect agreement with the result from the global rovibrational analysis of OCS by Fayt et al. in J. Mol. Spectrosc. 136 , 233–266 (1986). The wavenumber list of the main band is given. The reliability of the calibration accuracy in a high-resolution commercial instrument Bruker IFS 120 HR is examined.

Large aperture cube corner interferometer with a resolution of 0.001 cm −1

The interferometer of the Fourier transform spectrometer at the University of Oulu has been modified so that the maximum instrumental resolution is better than 10(-3) cm(-1). The resolution of the previous interferometer was 4.5 x 10(-3) cm(-1). The present interferometer consists of large cube corner mirrors and a large Mylar beam splitter. Each corner mirror has been made with three flat mirrors on an adjustable supporting frame. The interferometer was already in practical use in 1985. The first spectra (H(2)O, CO(2), N(2)O, OCS) recorded on this interferometer have been presented in HANDBOOK OF INFRARED STANDARDS WITH SPECTRAL MAPS AND TRANSITION ASSIGNMENTS BETWEEN 3 AND 2600 microm, G. Guelachvili and K. Narahari Rao, Eds. (Academic, New York, 1986).

Analysis of the ν1 band of CH3I

Abstract The rotational structure of the infrared band ν 1 of CH 3 I has been studied at a resolution of 0.04 cm −1 using a grating spectrometer. In the analysis including 470 lines a resonance, explained to be caused by ν 2 + 2 ν 6 ±2 , has been taken into account. The molecular constants derived include, e.g., α 1 A = 0.051129(14) cm −1 and α 1 B = 0.0983(9) × 10 −3 cm −1 .

A precise determination of the A0 rotational constant of propyne

Abstract In a previous paper (G. Graner et al., Mol. Phys. 64, 921–932 (1988)), a preliminary value of the A0 rotational constant of propyne was obtained by combining data from three rovibrational bands: ν10, ν8 + ν10, and the hot band (ν10 + ν8)±2 − ν10. In the present work, this value has been improved by an order of magnitude by using a better Fourier spectrum of ν10 and tunable diode laser spectra of the two other bands. Although most of the accurate data available still concern combination differences between K = 0 and K = 3, it has been possible to extract useful pieces of information from the pairs (1,4), (2,5), (3,6), and (4,7). The preferred values obtained are A0 = 5.308410(100) cm−1 and DK0 = 9.83(24) × 10−5 cm−1.