D. Goorvitch

Updated line parameters for OH X2II–X2II (ν′',ν′) Transitions

Abstract New spectral line parameters have been generated for the OH X 2 II–X 2 II transitions for Δv = 0.., 6, with v ′ = 0.., 10, and J max = 49.5. HITRAN type line parameter sets with low intensity cutoffs are provided at 296 and 6000 K. Recent improvements in line intensities and line positions have been incorporated into the calculations.

Nitric-acid band intensities and band-model parameters from 610 to 1760 cm −1

A set of 59 spectra of pure nitric acid was obtained at temperatures ranging from 236 to 294 K using path lengths from 10 to 50 cm and pressures from 0.05 to 1.1 Torr. No strong temperature dependencies were observed over the range of our measurements. Absorption coefficients and mean line-spacing parameters were determined at each 1-cm−1 interval in the three strong bands at 5.9, 7.5, and 1.3 μm by using a two-parameter random-band model. The resulting intensities for these bands are 1530 ± 100, 1383 ± 70, and 692 ± 35 cm−2 amagat−1, respectively. In addition, the absorption coefficients were determined in the three weak bands at 8.3, 13.2, and 15.5 μm. The band intensities derived are 44 ± 4, 45 ± 4, and 50 ± 5 cm−2 amagat−1, respectively.

For infrared spectrophotometry of Jupiter and Saturn

Abstract Infrared spectral observations of Mars, Jupiter, and Saturn were made from 100 to 470 cm−1 using NASAs G. P. Kuiper Airborne Observatory. Taking Mars as a calibration source, we determined brightness temperatures of Jupiter and Saturn with approximately 5 cm−1 resolution. The data are used to determine the internal luminosities of the giant planets, for which more than 75% of the thermally emitted power is estimated to be in the measured bandpass: for Jupiter LJ = (8.0 ± 2.0) × 10−10 L⊙ and for Saturn LS = (3.6 ± 0.9) × 10−10. The ratio R of thermally emitted power to solar power absorbed was estimated to be RJ = 1.6 ± 0.2, and RS = 2.7 ± 0.8 from the observations when both planets were near perihelion. The Jupiter spectrum clearly shows the presence of the rotational ammonia transitions which strongly influence the opacity at frequencies ≲250 cm−1. Comparison of the data with spectra predicted from current models of Jupiter and Saturn permits inferences regarding the structure of the planetary atmospheres below the temperature inversion. In particular, an opacity source in addition to gaseous hydrogen and ammonia, such as ammonia ice crystals as suggested by Orton, may be necessary to explain the observed Jupiter spectrum in the vicinity of 250 cm−1.

Foreign-gas collision broadening of the far-infrared spectrum of water vapor

The far-infrared rotational spectrum of H216O has been studied in the spectral range 25–112 cm−1 to measure the foreign-gas collision-broadened linewidths. Measurements of 17 lines broadened by nitrogen and 21 lines broadened by oxygen are reported. The measurements were made at 297 K. From these data, the widths due to air broadening are obtained. The experimental results are compared with recent theoretical calculations and with the case of a constant linewidth, equal to the average experimental width. There is some correlation between the relative experimental linewidths and the theoretical predictions. However, the simple assumption of a constant value for the collision-broadened linewidths gives a better representation for the case of N2- and O2-broadened linewidths than do present detailed theoretical calculations.

Spectral irradiance calibration in the infrared. III - The influence of CO and SiO

We describe first efforts to establish a network of calibrated infrared spectra of «standard stars» suitable for calibration of at least low-resolution infrared spectrometers using ground-based, airborne, and satellite-borne broadband sensors. The focus of this paper is on the crucial 5-8 μm region, inaccessible from the ground, in K and M giants. In this region the fundamental bands of CO and SiO cause substantial departures from featureless pseudo-continua. These departures are, of course, well-known to stellar atmosphere theorists. However, they are still ignored by many astronomical infrared photometrists and spectroscopists who assume that these bright stars can be represent by blackbodies at their effective temperatures

The 2-μm polar haze of Jupiter

High-resolution spectroscopy of the polar regions of Jupiter revealed the spectral characteristics of the polar haze and numerous CH4 absorption lines in the range 4200–4700 cm−1. We present model spectra, which were constructed including CH4 lines, hydrogen pressure-induced opacity, and haze layers. From comparison with the model, we conclude that for optically thin haze models the polar haze is located mainly between the pressure levels of 70 and 5 mbar, and for opaque haze models the top of the haze layers should be around the 15-mbar level. The polar haze is found to be widely distributed in the south and north polar region, and is not particularly associated with auroral activities. The 2-μm broad-band image of the polar haze is found to be very similar to that of an 8900-A image. The reflectance of the haze increases almost linearly between 4200 and 4600 cm−1, maintains a flat value between 4600 and 4800 cm−1, and decreases rapidly from 4800 to 4900 cm−1.

Temperature dependence of HNO 3 absorption in the 11.3-μm region

Laboratory spectra have been obtained for HNO3 with a Michelson-type Fourier transform interferometer using absorption cells with path lengths of 10.3, 25.5, and 49.8 cm at temperatures of 240, 248, 283, and 294 K. The measurements lead to a total band intensity value of 642 plus or minus 5% per sq cm amagat, which is a temperature independent value after the gas density correction has been made. However, the temperature dependence of the spectral absorption coefficients is apparent in the 885 kayser region.

Collision-induced absorption in the far infrared spectrum of Titan

Abstract The effects of collision-induced absorption on the far infrared spectrum of Titan have been investigated. After a review of the procedure for the theoretical calculation of the N 2 translation-rotational spectrum, new results for the temperature range of 70 to 120°K are reported. These are used as input data for a simple atmospheric model in order to compute the far infrared radiance, brightness temperature, and spectral limb function. This source of opacity alone is not capable of explaining the Voyager results. When the collision-induced methane is included, the results are in closer agreement in the range between 200 and 300 cm −1 , suggesting that a more complete treatment of collision-induced absorption including particularly CH 4 N 2 , N 2 H 2 , and H 2 H 2 results, may provide sufficient opacity to reduce or obviate the need for opacities due to clouds or aerosols in order to explain the observed spectra.

Interferometrically Measured Thorium Lines between 2747 and 4572 Å

Interferometrically measured wavelengths tabulated for Th lines in 2747-4572 A range, using liquid nitrogen cooled hollow cathode lamp and Fabry- Perot interferometer

HCl vibrational fundamental band: Line intensities and temperature dependence of self-broadening coefficients

Abstract Self-broadening in the vibrational fundamental of HCl is inversely proportional to the temperature for transitions which lie near the Boltzmann rotational maximum and becomes monotonically less temperature-dependent as the rotational quantum number increases. We have determined the rotationless transition moment to have the value of 5.57 ± 0.13 × 10 −3 (Debye) 2 and the first Herman-Wallis factor, C = −2.543 ± 0.019 × 10 −2 .