Jacob H. Miller

Intensity measurements and rotational intensity distribution for the oxygen A-band

Abstract Quantitative measurements of intensities and half-widths have been made for individual rotational lines of the atmospheric oxygen A-band. The total band intensity, as derived from the line intensity measurements, is 532 cm-1 km-1 atm-1 STP. The line half-widths at half intensity were determined by two methods for the PQ and PP branch lines and are found to vary from about 0.05 cm-1 atm-1 near the origin to 0.04 cm-1 atm-1 for high K″ values. The rotational intensity distribution is demonstrated to conform more closely to the theoretical Honl-London factors calculated by either Schlapp or by Watson rather than those found experimentally by Childs and Mecke.

Intensity measurements, self-broadening coefficients, and rotational intensity distribution for lines of the oxygen B band at 6880 Å

Abstract Quantitative measurements of intensities and half-widths were made for individual rotational lines of the atmospheric oxygen B band. The total band intensity, as derived from the line intensity measurements, is 40·8±0·6 cm −1 km −1 atm −1 STP. As had been previously found in this laboratory for the oxygen A band, the relative line intensities conform closely to the rotational distribution calculated by either Schlapp or by Watson. The line half-widths at half-intensity were determined for oxygen self-broadening for the P Q and P P branch lines and for a few R Q and R R branch lines near the band origin, and were found to vary from 0·064 cm −1 atm −1 at J ′ = 1 to 0·042 cm −1 atm −1 at J ′ = 25.

A laboratory atlas of the 5ν1 NH3 absorption band at 6475 Å with applications to Jupiter and Saturn

Abstract The 5 ν 1 absorption band of NH 3 is displayed from 6418 to 6550 A. The total band intensity has been measured: S B = 0.66 cm −1 m −1 amagat −1 . Line intensities and self-broadening coefficients have been measured for some of the prominent lines. Our line intensities are in good agreement with those of Rank et al . (1966) , but are about 2 times greater than those of Mason (1970) . The spectrum displayed was obtained photoelectrically at a pressure of 0.061 atm, and shows many more lines than the spectrum obtained by McBride and Nicholls (1972a) at a pressure of 0.39 atm. Therefore, our new measurements can provide the basis for making a more complete rotational analysis than those of McBride and Nicholls (1972a) . Since the total band absorption has previously been measured by others on moderate resolution photoelectric scans of the spectra of Jupiter and Saturn, we can use the band intensity to derive the NH 3 abundance in the atmospheres of these two planets. The NH 3 abundances in a single vertical path obtained by this method are about 10m amagat for Jupiter and 2m amagat for Saturn. These results are in agreement with previous results obtained from higher resolution photographic spectra.

Intensity measurements of the 1 μ CO2 bands

Abstract The quantitative intensity of the weak CO2 triad in the 1 μ spectral region has been measured. Integrated R-branch intensities were obtained by using pressure broadening techniques with absorbing paths up to 4·8 km-atm. The R-branch intensities for the transitions 20°3«00°0, 12°3«00°0, and 04°3«00°0 are 1·27, 3·50, and 0·59 cm−1 km−1 atm−1 S.T.P., respectively. Intensities and half-widths of the J4 through J22 lines in the P-branch of the 12°3«00°0 transition have been determined.

Intensity measurements for the (2, 0) γ-band of O2, b1Σ+g−X3Σ-g

Abstract Quantitative intensity measurements have been made for the oxygen γ-band at 6280 A. Intensities for 19 individual rotational lines of the PP and PQ branches and the intensity of the combined RR and RQ branches are reported. The band intensity, Sv′v″, is found to be 1.52±0.07 cm-1km-1atm-1 (STP).

Does spectroscopic evidence require two scattering layers in the Venus atmosphere

The phase variation of lines in the 7820 and 7883 A CO2 bands has been interpreted by Hunt using an inhomogeneous, anisotropic scattering model of the Venus atmosphere. He concluded that the Venus atmosphere contains two scattering layers. We show that the observed phase variation may be due to the strong backward lobe in the Venus cloud phase function and that two cloud layers are not necessarily required.

Intensity of the 1·6 μ bands of CO2

Quantitative measurements of intensity and half-width have been made for over 30 lines in each of the C12O162 bands of the 1·6 μ tetrad. The total band intensities, derived from the line intensity measurements, for the (30°1)I, (30°1)II, (30°1)III, and (30°1)IV bands are 127, 1050, 1070, and 122 cm-1 km-1 atm-1 STP, respect ively. The observed rotational line intensity distribution of the (30°1)III band was found to depart slightly from the Boltzmann distribution. A satisfactory fit to the observed distribution was obtained by applying a weak vibration- rotation interaction. The widths of the lines of the (30°1)IV band are found to be 50 per cent larger than those of the other members of this tetrad.

Theoretical interpretation of the 0.7820 μm CO2 band and 0.8226 μm H2O line on Venus

Abstract We have analyzed the P6, P8, and P10 lines in the 0.7820 μm CO2 band of Venus using a scattering model. Our new results compare favorably with previous results from the 1.05 μm CO2 band. We considered nonabsorbing and absorbing clouds. We found that the anisotropic scattering mean free path for both models at the 0.2atm level is between 0.55 and 0.73km, a range close to the value of 1 km for terrestrial hazes. We used our scattering models to synthesize the 0.8226 μm H2O line, assuming that the clouds are composed of sulfuric acid drops, and found our nonabsorbing cloud required a sulfuric acid concentration of 82% by weight, while our thicker absorbing cloud required a concentration of 89%. A comparison of the variation of optical depth with height for our cloud models with the variation reported by Prinn (1973, Science 182, 1132–1134) showed that, within a factor of 2, the variation for Prinns thinnest cloud agreed with ours. Whitehill and Hansen (1973, Icarus 20, 146–152) have recently confirmed the work of Regas et al. (1973a, J. Quant. Spectry. Radiative Transfer 13, 461–463) which showed that two cloud layers are not required to explain the CO2 phase variation of Venus. Prinns recent photochemical study of sulfuric acid clouds further supports a single, continuous cloud layer in the line formation region instead of two cloud layers with an extensive clear region between. The single layer model appears more likely because the maximum particle density in Prinns cloud occurs in the clear region between the two layers in the models of Hunt (1972, J. Quant. Spectry. Radiative Transfer 12, 405–419) and Carleton and Traub (1972, Bull. Amer. Astron. Soc. 4, 362.).

Cryogenic Testing Of Mirrors For Infrared Space Telescopes

An optical test facility has been built for testing candidate mirror materials for the Shuttle Infrared Telescope Facility (SIRTF). Mirrors as large as 66 cm in diameter can be tested at temperatures down to about 10K for changes in optical figure of a fraction of a wave from their room temperature figure. Tests of two fused silica mirrors, 50 cm in diameter, are underway. The test mirror is heat sunk to the helium reservoir with copper straps whose connection to the mirror is accomplished by soldering individual strands of copper to small silver spots diffused into the unfigured side of the mirror. This permits relatively fast, conductive cooling of the mirror. In the first test, cooling from 300 to 80K took 4 days; cooling from 80 to 12.5K took 24 hours. Optical access to the cold mirror is through a small (5 cm diameter) glass port in the vacuum chamber placed a few cm short of the radius of curvature of the mirror. A Shack interferometer is used to examine the mirror figure throughout the cool-down. Interferograms are photographed and the fringe patterns are digitized. Contour plots of mirror figure are then calculated using the University of Arizonas FRINGE program on our CDC 7600 computer. Preliminary analysis of interferograms of one of the mirrors shows very little change in figure between 293K and 10.5K (change in rms OPD=0.027 waves).

Ultra Lightweight Mirror Performance At 8 Degrees Kelvin

In response to technology needs for infrared (IR) telescopes operating at cryogenic temperatures, Eastman Kodak Company has developed a 0.5-meter (m), ultra lightweight, frit bonded, fused silica mirror capable of being scaled to a larger size that would provide a fast aspheric, smooth, low scatter optical surface. This mirror has been evaluated by Kodak at a temperature of 100 degrees Kelvin (°K). This paper reports on a continued evaluation of the mirror jointly by Kodak and Ames Research Center (ARC) to a temperature of 8°K. Analysis of common interferograms by independent processing hardware and software has been carried out by Kodak and ARC. The results of both processes are compared and reported.