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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Vertical profiles of CO and CH4 in the lower and middle troposphere over the Eastern United States January 1978

Samples of tropospheric air were obtained over the Eastern United States during January of 1978. These samples were analyzed by gas chromatography using flame ionization detection to produce vertical profiles of carbon monoxide and methane from the surface to 8 km. The carbon monoxide mixing ratios at 35 deg N and 45 deg N agree with previously published values; however, the mixing ratio at 25 deg N was significantly lower than most published values. The methane mixing ratio was weakly dependent on latitude and has an average value of 1.64 ppm.

Reichle, H. G., Jr.↗
NASA NTRS1980

Detection of a CH4 atmosphere on Pluto

A ratio spectrum of Pluto shows methane absorption bands at 6200, 7200, 7900, 8400, 8600, 8900, and 10,000 A. The heavy saturation of the 8900 band as compared to the other bands indicates a gaseous origin for the observed absorptions. A total methane abundance of 80 + or - 20 m-am is derived, and an upper limit to the total pressure of approximately .05 atm is set. The methane atmosphere would be stable if the mass of Pluto is increased 50% over its present value and its radius is 1400 km. A heavier gas mixed with the methane atmosphere would also aid its stability.

Fink, U.↗
NASA NTRS1980

Radio-frequency observations of interstellar CH4 and HC5N

New (C-12)H4 transitions were detected at 21,303 and 94,089 MHz in emission from Orion A, and temporal variations of intensity were observed among several velocity components at 76,700 MHz. An HC5N transition at 21,301 MHz was also detected in emission from IRC +10216.

Fox, K.↗
NASA NTRS1982

Line intensities from band and diode laser measurements: Neutrino 4 of CH4

The experimental data and theoretical work on the 7.7 micron band of methane are reviewed. This band is particularly relevant in studies of the atmospheres of Jupiter, Saturn and the other outer planets. Methane spectra taken from the infrared spectrometer (IRIS) aboard Voyager, and a temperature profile derived by inverting those data, both for hydrogen and methane are presented.

Fox, K.↗
NASA NTRS1982

Current band model studies of CH4 at wavelengths less than 2.5 microns

Band model theories are used to calculate the transmission of the methane spectrum. In a band model the monochromatic absorption coefficient over a small wavelength interval is replaced, and an average pressure coefficient is introduced. Two main types of band models were developed. The first is the 'regular' band model, in which the lines in a band are presumed evenly spaced; this is also called the Elsasser band model. In the second type of band model, the lines are randomly spaced; this is often referred to as the Mayor-Goody band model. The methane spectrum is sufficiently irregular that the second band model, the irregular band model, should apply.

Fink, U.↗
NASA NTRS1982

Long-pathlength absorption spectroscopy of CH4

Infrared spectra of methane and ammonia are taken. The methane data base accumulated is described. The spectral region from 4,000 to 6,500 cm is covered at moderate resolution (0.15 cm), working at three temperatures (118, 191, and 272K), and with the (pressure - pathlength) product ranging over a factor of a thousand. Methane spectra broadened by hydrogen and helium have also been taken. Normalized spectra are stored on magnetic tapes, at a resolution slightly better than 0.25 cm.

Silvaggio, P.↗
NASA NTRS1982

The abundances of CH4, CH3D, NH3, and PH3 in the troposphere of Jupiter derived from high-resolution 1100-1200/cm spectra

High-resolution spectra of the 1100-1200/cm region of the central part of Jupiter obtained in March 1980 and April 1981 are analyzed. The best fit NH3 distribution curve reveals a higher than solar mixing ratio, the abundance of NH3 to that of H2 being (3.3 + or - 1.7) x 10 to the -4th, below the 147 K layer (greater than 0.6 atmosphere). If NH3 ice particles are introduced as an opacity source, the NH3 mixing ratio below the 147 K layer can be lowered, but the fit is worse than that given by the model that excludes NH3 ice particles. The best fit PH3 distribution curve exhibits a PH3/H2 mixing ratio of (8.3 + or - 2.0) x 10 to the -7th in the troposphere. In addition, a CH4/H2 mixing ratio of (2.5 + or - 0.4) x 10 to the -3rd is found in the troposphere.

Knacke, R. F.↗
NASA NTRS1987

Effects on H(-) production in a multicusp ion source by mixture of H2 with H2O, NH3, CH4, N2H4, and SF6

Effects of H(-) production in a multicusp ion source are measured by separately mixing with hydrogen small amounts (0.33-10 percent) of water, ammonia, methane, and hydrazine these are molecules which produce large amounts of H(-) via dissociative attachment (DA) resonances at higher electron energies. The mixing was done in a separate reservoir, with careful measurement of individual pressures. Experimental enhancements of 1.4 and less were observed, whereas calculated enhancements, using accurate DA cross sections for ground-state H2, should have produced factors of 1.5, 3.0, 1.3, and 2.4 enhancements for water, ammonia methane, and hydrazine, respectively, at a mean electron energy of 1.0 eV in the extraction region. The difference is accounted for by including, in the enhancement calculation, vibrationally and rotationally excited H2 molecules, with v-double prime = 5-11, and J-double prime = 0-5, and the large DA cross sections for the excited H2 (v-double prime, J-double prime). The relative populations of H2 (v-double prime, J-double prime) thus obtained are found to be substantially smaller than those predicted by theoretical calculations. The effect on H(-) current was also studied by mixing small amounts of SF6 with H2. A 1.5 percent mixture was found to reduce the H(-) output by one half.

Orient, O. J.↗
NASA NTRS1989

Reference model for CH4 and N2O and trends

Data from the Stratospheric and Mesospheric Sounder on Nimbus 7 were used as the basis for a model of the abundances of nitrous oxide and methane in the stratosphere. A version of this was produced two years ago (Taylor, Dudhia, and Rodgers - hereafter called the original paper) and in this new paper some of the possible error sources and long term trends are considered in more detail. The principle source of error in the SAMS retrievals is thought to be the use of climatological ozone profiles to invert the temperature profile data. However, it was found that the effect is too small, and of the opposite sign, to explain the discrepancies between satellite and in situ measurements, noted in the original paper. As expected, no systematic trends which exceed the estimated error in the data are found in either methane or nitrous oxide.

Taylor, F. W.↗
NASA NTRS1990

Shock temperature measurements of planetary ices - NH3, CH4, and 'synthetic Uranus'

Shock temperature measurements have been performed on several materials which have relevance to the modeling of the outer planets. These materials are methane, ammonia and a mixture of water, ammonia, and isopropanol known as synthetic Uranus. Temperatures have been measured in these materials over the pressure range 33-76 GPa for which there also exists measurements of equation of state and electrical conductivity. The temperatures are found to agree well with available calculations, with small discrepancies between data and theory ascribed to energy absorbing processes such as dissociation and molecular ionization.

Radousky, H. B.↗