A.G. Maki

Heterodyne frequency measurements of CO and OCS beyond 2100 cm−1

Abstract Infrared heterodyne frequency measurements are given for absorption lines of the 04 0 0-00 0 0 band of OCS and the fundamental band of CO. Transition frequencies of several isotopomers of CO are given. The frequency measurements were based on doubled CO 2 laser radiation used as a local oscillator and as a frequency standard. Tables of wavenumber standards based on both OCS and CO absorption lines are given.

Infrared Spectrum of the ν6 and ν7 Bands of Deuterated Nitric Acid (DNO3)

Abstract The high-resolution Fourier transform infrared spectrum of deuterated nitric acid (DNO 3 ) has been measured in the ν 9 region between 320 and 384 cm −1 with a resolution of 0.0035 cm −1 . As expected for an out-of-plane vibrational fundamental, and accompanying hot bands, only C -type transitions were observed. Using a Watson Hamiltonian, 1772 infrared transitions have been assigned and fitted to give 9 rovibrational constants for the v 9 = 1 state. With the knowledge of these constants, an analysis was made of 598 assigned transitions for the hot band 2 ν 9 - ν 9 in order to provide rovibrational constants for the v 9 = 2 state. Both bands show no evidence of perturbation, although the v 9 = 2 state is expected to be crossed by the v 6 = 1 state above J = 40. The band centers are at 343.8496 ± 0.0001 cm −1 for ν 9 and 333.7331 ± 0.0001 cm −1 for 2 ν 9 - ν 9 .

Infrared and microwave spectra of SrO and BaO

Abstract The high-resolution infrared spectrum of strontium oxide has been observed in a low-pressure flame. A total of 43 Δ v = 1 transitions has been measured for the three most abundant isotopomers of SrO. New microwave measurements have also been made for SrO and BaO using a laser ablation technique. The measurements were combined in a least-squares fit with other data taken from the literature to obtain a set of Dunham potential constants and Dunham rovibrational coefficients. The accurate values obtained for the first terms in the Dunham potential function enabled us to calculate several higher-order rovibrational constants that could not be determined from a direct fit to the experimental data. Constants, determined in a parallel fashion, are given for SrO, BaO, CaO, and MgO. The nuclear quadrupole coupling constants have been determined for 87 SrO, v = 0, 1, and 2, and for v = 0 of 135 BaO and 137 BaO.

Heterodyne frequency measurements of 12C16O laser transitions near 2050 cm−1

Abstract New heterodyne frequency measurements of 12C16O laser transitions were made in the 1995 to 2082 cm−1 (59.81 to 62.39 THz) region. Frequencies of 23 transitions (with lower vibrational quantum numbers, v″, ranging from 1 to 4) were measured. New constants for these low-lying vibrational levels were determined by fitting these data (along with sub-Doppler measurements by Pollock et al. (J. Mol. Spectrosc., 99, 357–368 (1983)), rotational transition measurements, and FTS measurements from Guelachvili et al.(J. Mol. Spectrosc., 98, 64–79 (1983)) to the Dunham expression. Frequency calibration tables calculated from these new constants are reported. These tables provide accurate transition frequencies for the CO laser stabilized to the Doppler-broadened gain profile.

Extension of heterodyne frequency measurements on OCS to 87 THz (2900 cm-1)

Abstract Heterodyne frequency measurements have been extended to 87 THz by using the CO overtone laser as a transfer oscillator. Measurements were made on the 11 1 1-01 1 0 band of OCS at 2900 cm −1 . Frequency differences were measured between a tunable diode laser (TDL) which was locked to OCS absorption lines and a stabilized overtone laser which was referenced to stabilized CO 2 lasers. These measurements have been combined with earlier Fourier transform (FT) measurements and a comprehensive set of data from frequency and FT measurements on lower lying transitions in OCS. This permits obtaining accurate values of transition frequencies for calibration of spectra in the 3.4-μm region.

High resolution FTIR measurement and analysis of the ν8 band of deuterated nitric acid (DNO3)

Abstract The infrared spectrum of the ν 8 band of deuterated nitric acid (DNO 3 ) has been measured with a resolution of 0.002 cm −1 in the frequency range of 730 to 794 cm −1 . A total of 1888 assigned transitions have been analyzed to provide rovibrational constants for the upper state with a standard deviation of 0.00022 cm −1 . In the course of the analysis, the constants for the ground state were improved. Because of the absence of perturbations, the constants can be used to accurately calculate the infrared line positions for the band. The band is C -type with a band center at 762.8738 ± 0.0001 cm −1 . As was found for ν 8 of HNO 3 , the P branch is much weaker than the R branch. Effective Herman-Wallis correction factors are given for the band.

Pressure Dependent Lineshift Measurements on OCS

!A computer-controlled, frequency offset-locked spectrometer using a tunable diode laser is described and new measurements on carbonyl sulfide (OCS) are given to illustrate its use. Two OCS absorption lines, R( 3) and P( 30), have been measured for the 02°0-0000 vibrational transition near IO pm. An average pressure-induced shift coefficient of -0.37 * 0.04 kHz/Pa (-49 ? 5 kHz/Torr) was observed for the two lines. The self-broadening coefficient for each line has also been measured. 0 1991 Academic Press, Inc.