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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
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NASA NTRS1980

Far infrared measurement of stratospheric HCl

Thermal emission from three rotational lines of H(Cl-35) and H(Cl-37) was observed with a Fourier transform spectrometer from a balloon platform at 28.9 km. The measured HCl line-of-sight density at 1.9 deg elevation above 28.9 km is 4.7 + or - 1.3 x 10 to the 15th/sq cm, implying an average volume mixing ratio of 0.8 + or - 0.2 x 10 to the -9th at the mean sampling altitude of 32.5 km. For a uniform mixing ratio model, this corresponds to a vertical column density of 2.4 + or - 0.6 x 10 to the 14th/sq cm. This result is in reasonable agreement with near infrared spectroscopic determinations and an abundance from a chemical sampling technique of HCl at this altitude; a pressure modulator radiometer measurement yields a significantly higher amount of HCl.

Chance, K. V.↗
NASA NTRS1981

Fourier spectroscopy on planetary missions including Voyager

In the last dozen years spaceborne Fourier transform spectrometers have obtained infrared emission spectra of Earth, Mars, Jupiter, Saturn and Titan as well as of the Galilean and other Saturnian satellites and Saturn's rings. Intercomparisons of the properties of planetary atmospheres and of the characteristics of solid surfaces are now feasible. The principles of remotely sensing the environment on a planetary body are dicussed. Special consideration is given to the most recent results obtained by the Voyager infrared investigation on the Saturn system.

Hanel, R. A.↗
NASA NTRS1980

Progress report on the ATMOS sensor - Design description and development status

The Atmospheric Trace Molecule Spectroscopy program is a multiflight shuttle borne investigation designed to determine, on a global scale, the compositional structure and spatial variability of the upper atmosphere using the technique of high resolution infrared absorption spectroscopy. The measurement approach is based on an advanced Fourier Transform Spectrometer capable of obtaining high sensitivity spectral measurements of the atmosphere over a wide spectral region (625-5000 kaysers; 2-16 microns) at high spectral resolution (0.01 kaysers) and vertical height spatial resolution (2 km). Additional elements of the sensor system include a suntracker, a telescope, a mechanically cooled (Hg,Cd)Te detector, and a data handling subsystem with a 16 Mbit/s PCM output. A description is given of the sensor design, including performance predictions, followed by a brief summary of the current technical status of the development effort.

Morse, P. G.↗
NASA NTRS1981

Line parameters of methane from 2385 to 3200/cm

A list of new methane line parameters for the 2385-3200 cm region included in the Air Force Geophysical Laboratory's compilation of molecular line parameters is presented. Line positions were determined by computer computations from Fourier transform spectrometer data using a Kitt Peak subroutine. With the exception of class IV lines, all line strengths were determined by the method of equivalent widths. Additional line strengths were measured from spectra taken at cold sample temperatures so that lower state transition energies could be determined experimentally. Observed line positions and strengths are given for 8076 absorptions with strengths greater than 3.3 x 10 to the -24 cm/molecule.

Toth, R. A.↗
NASA NTRS1981

Anomalous C-12H4:C-13H4 strengths in 3 ny sub 3

The C-12:C-13 ratios in the atmospheres of the outer planets are important parameters with which to test models for isotope formation and fractionation during the early history of the solar system, yielding insight into processes occurring in the primitive solar nebula. The 3 ny sub 3 spectra of methane were obtained using the Kitt Peak Solar Fourier Transform Spectrometer and a 6 m White cell. The experimental results are summarized in a table. The strength ratios for the R-branch of 3 ny sub 3 exhibit strong anomalies, with C-13H4 lines consistently weaker than their C-12H4 counterparts. The C-12:C-13 abundance ratios for the atmospheres of Jupiter and Saturn have been redetermined using the 3 ny sub 3 line-strength ratios measured.

Brault, J. W.↗
NASA NTRS1982

Laboratory molecular spectroscopy

The precision required in making spectroscopic measurements is discussed. Remarks are directed specifically to vibration-rotation spectra rather than continuum absorptions. The ultimate precision that is required for line positions is related to the width of the lines which may be no narrower than the Doppler width. The spectroscopic methods considered are those which are of the most general value to the astronomers; those which acquire and can handle large volumes of spectra in digital form, or in a form which is compatible with computer analysis, and in a form which is at least internally consistent. The use of dye laser, grating instruments, and the most versatile instrument for laboratory spectroscopy, the Fourier transform spectrometer is discussed.

Margolis, J.↗
NASA NTRS1982

Current Studies of CH4 from 2.5 to 7 microns

The 3.5 micron region of methane was analyzed. The positions and strengths of approximately 9000 absorption lines in the region from 2400 to 3200 cm were measured. Spectra were obtained at a resolution of 0.1 cm using the Fourier transform spectrometer and at 0.02 cm resolution using the four passed grating spectrometer. The analysis of the 3.5 micron region required the use of spectra of CH4 in other regions, therefore the methane spectrum from 1200 to 4700 cm is indicated. The method used for the compilation of line lists is demonstrated.

Brown, L.↗
NASA NTRS1981

Stratospheric HF and HCl observations /15 June 1981/

Balloon measurements of the stratospheric HF/HCl ratio are reported. Seven far-infrared rotational lines of HF and HCl were observed at elevation angles of 25, 18 and 8 deg by a far-infrared Fourier-transform spectrometer on board a balloon platform at 28.5 km. Analysis of line intensities yields an average HF/HCl ratio of 0.18 + or - 0.02 at an effective altitude of 33 km, with a water vapor mixing ratio of about 4 ppmv. Results are noted to be in reasonable agreement with the calculated profile of Sze and Ko (1981) with 4.5 ppmv H2O.

Traub, W. A.↗
NASA NTRS1981

Fourier spectroscopy on planetary missions including Voyager

For more than a decade, spaceborne Fourier transform spectrometers have been employed in investigations concerning the earth and other objects in the solar system. The wide spectral range at moderately high spectral resolution, the precise wavenumber and radiometric calibrations, and the reliability achieved by these instruments, have permitted scientific investigations which would otherwise have been impossible. Weight limitations and the long flight durations prohibited the use of highly sensitive, cryogenically cooled detectors on these missions. A brief review is presented of the evolution of the instruments known as IRIS (InfraRed Interferometric Spectrometer). The concept of remote sensing by infrared emission spectroscopy is discussed, and examples of results obtained with IRIS are presented. Attention is given to the most recent results from Voyager with emphasis on those from Titan.

Hanel, R. A.↗
NASA NTRS1982

Analysis of CO2 bands near 2600 per cm

The parameters of three bands of CO2 near 2600 per cm have been determined by the nonlinear least squares method of whole-band analysis. Careful modeling of the effect of the Fourier transform spectrometer on the spectrum has made it possible to reduce the difference between the observed and calculated spectra to values close to the estimated noise in the experimental spectrum. In particular, it is found necessary to model the effects of phase error even though these are difficult to observe in the experimental spectra.

Hoke, M. L.↗
NASA NTRS1982

Quantum assignments and intensity measures for methane between 1100 and 1800 per cm - A comparison between theory and experiment

The paper analyzes line positions and absolute line strengths of Blatherwick et al. (1979), based on moderately high resolution spectra of methane between 1100 and 1800 per cm, obtained using the Fourier transform spectrometer and the multiple-pass cold cell at the NASA Ames Research Center. Hamiltonian models are used to calculate theoretical relative line strengths, which, in combination with measured line strengths, yield integrated band strengths for the fundamentals v2 and v4. Ratios of calculated intensities to experimental intensities are analyzed, and the systematic deviations in the P- and R-branches of the v2 band are found to be represented by a Herman-Wallis type factor for Coriolis interactions. An analysis of ratios of calculated to experimental intensities of the v4 band yields a small correction to the Herman-Wallis factor.

Lutz, B. L.↗
NASA NTRS1982

Line positions and strengths of HDO in the 2400-3300 per cm region

The vibration-rotation spectrum of HDO in the 2400-3300 per cm region has been studied at 0.01 per cm resolution with a Fourier transform spectrometer. Values of the ground state levels and levels in the (100) and (020) states have been determined from the data. The ground state levels are fitted to a Watson-type Hamiltonian from which 17 rotational constants are obtained. Measurements of the strengths of over 1100 lines have been made using a nonlinear least-squares fitting technique, and 548 of these lines are analyzed to determine the band strengths, the coefficients of the F factors, and the Coriolis interaction parameters. The strengths of the A- and B-type (100) bands and the A- and B-type (020) bands are 53.2 + or - 0.9, 0.43 + or - 0.07, 6.00 + or - 0.54, and 2.75 + or - 0.12 per sq cm per atm at 296 K, respectively.

Toth, R. A.↗
NASA NTRS1983

Atlas of high resolution infrared spectra of carbon dioxide, February 1983

A long path, low pressure laboratory spectrum of carbon dioxide is presented for the spectral region 1830 to 2010/cm. The data were recorded at 0.01/cm resolution and room temperature with the Fourier transform spectrometer in the McMath solar telescope complex at Kitt Peak National Observatory. A list of positions and assignments is given for the 1038 lines observed in this region. A total of 30 bands and subbands of 12C16O2, 13C16O2, 12C16O18O, 12C16O17O, and 13C16O18O were observed.

Benner, D. C.↗
NASA NTRS1982

Ground-based infrared spectroscopic measurements of atmospheric hydrogen cyanide

A number of lines of the nu-3 band of hydrogen cyanide have been detected in solar absorption spectra recorded near sunrise and sunset at Kitt Peak National Observatory (elevation 2095 m) with a 0.01/cm resolution Fourier transform spectrometer. Analysis of two of the strongest and best isolated lines has led to a value of 2.73 x 10 to the 15th molecules/sq cm for the vertical column abundance of HCN above Kitt Peak. The accuracy of this value is estimated as + or - 25%. This result, combined with the stratospheric concentration of HCN derived by Coffey, Mankin, and Cicerone (1981), yields 166 parts per trillion by volume for the average mixing ratio of HCN between 2 and 12 km. This is the first determination of the HCN concentration in the nonurban troposphere.

Rinsland, C. P.↗
NASA NTRS1983

Line positions and strengths in the /001/, /110/, and /030/ bands of HDO

A Fourier transform spectrometer of 0.01/cm resolution has been used to study the vibration-rotation spectrum of HDO in the 3250-4370/cm region, and a nonlinear least squares fitting technique has been employed in measurements of the strengths, positions and pressure-broadening parameters of over 1400 lines. In addition to determining values of both the ground state levels and levels in the (001), (110), and (030) states, an analysis is undertaken of the strengths of 953 lines in order to establish band strengths, F factor coefficients, and Fermi interaction parameters. Detailed results are presented in tabular form.

Toth, R. A.↗
NASA NTRS1983

N2 broadening parameters of ozone at 9.6 microns

Pressure-broadening coefficients were determined for 156 O3 absorption lines made with the Fourier-transform spectrometer at the McMath Solar Telescope of the Kitt Peak National Observatory in the 9-micron region, with a resolution of 0.005/cm. O3 prepared from O2 by silent arc discharge and collected on cold silica gel was held at stable concentrations over 50 percent in a glass or stainless-steel cell with a rock-salt window, and broadened with dry N2. Interferograms were made in several scans of the interferometer during 30 min. The pressure-broadening coefficients were calculated by an iterative least-squares approach, a synthetic spectrum was constructed and compared to the actual spectrum, and the parameters were varied to achieve the best fit. It is shown that the estimated precision of the values reported is about 7 percent, and that the deviation from the theoretical calculations of Tejwani and Yeung (1975) averaged 7.6 percent (a small number of large discrepancies having been excluded).

Margolis, J. S.↗
NASA NTRS1983

High-resolution infrared spectroscopy of planetary atmospheres

Various techniques for high-resolution infrared spectroscopy of planetary atmospheres are reviewed. Resolving powers of a million are now possible at 1-5 microns with Fourier transform spectrometers and at 10 microns with heterodyne spectrometers. The extension of high-resolution spectroscopy to the far-infrared is currently under development. The role of ground-based high-resolution spectroscopy compared to observations by spacecraft is discussed.

Tokunaga, A. T.↗
NASA NTRS1983

Absolute intensity measurements of the (11/1/0)II-00/0/0 band of (C-12)(O-16)2 at 5.2 microns

A nonlinear least-squares fitting procedure has been used to derive absolute intensities for lines in the P, R, and Q branches of the (11/1/0)II-00/0/0 band of (C-12)(O-16)2 (band center = 1932/cm) from long-path 0.01/cm resolution laboratory spectra. The spectral data were recorded at room temperature and low pressure (less than 10 torr) with the Fourier transform spectrometer in the McMath solar telescope complex at Kitt Peak National Observatory. The observed line intensities were analyzed to derive the vibrational band intensity and F-factor coefficients. To obtain a good fit to the data, it was necessary to include terms in the expression for the F factor, which account for Coriolis-type and Fermi-type interactions and centrifugal distortion effects.

Rinsland, C. P.↗