Pressure-induced microwave absorption in N sub 2.
Pressure induced microwave absorption in molecular N for various temperatures, determining dielectric loss, absorptivity and quadrupole moment
Ho, W.↗
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Pressure-induced microwave absorption of nonpolar gases.
Collisionally induced microwave absorption by nonpolar gases, discussing dimer absorption
Foley, H. M.↗
An optical absorption cell with variable path length and temperature.
Optical absorption cell with variable path length and temperature for measuring absorption coefficients of gases at low and high temperatures
Cann, M. W. P.↗
An absorption spectrum amplifier for determining gas composition
Compositions of gas samples are frequently studied by laser absorption spectroscopy. Sensitivity is improved by two orders of magnitude when absorption cell is placed inside an organic-dye laser cavity.
Zalewski, E. F.↗
Estimation of microwave absorption in the Jupiter atmosphere
A procedure for estimating the microwave absorption loss of the Jupiter atmosphere is presented. Estimation of microwave absorption by planetary atmospheres involves two different investigative disciplines (1) the determination of an acceptable model of the atmosphere itself and (2) the determination of the microwave attenuation rate applicable to each different volume sample of the atmosphere, and the integration of this loss over the varying radio propagation path for any given entry trajectory to obtain the total loss.
Coombs, W. C.↗
Measurement of temperature profiles in flames by emission-absorption spectroscopy
An investigation was conducted to explore the use of infrared and ultraviolet emission-absorption spectroscopy for determination of temperature profiles in flames. Spectral radiances and absorptances were measured in the 2.7-micron H2O band and the 3064-A OH band in H2/O2 flames for several temperature profiles which were directly measured by a sodium line-reversal technique. The temperature profiles, determined by inversion of the infrared and ultraviolet spectra, showed an average disagreement with line-reversal measurements of 50 K for the infrared and 200 K for the ultraviolet at a temperature of 2600 K. The reasons for these discrepancies are discussed in some detail.
Simmons, F. S.↗
Radioastronomical measurement of absorption
Diurnal and seasonal absorption curves measured by a radio astronomical method at Alma-Ata during the IQSY (1964-1965) are submitted. The apparatus is described. The dependence of absorption on solar flares is also indicated.
Yakovets, T. K.↗
Cosmic ray variations during PCA type absorption
It is shown based on data on the cosmic-ray neutron component, ionospheric soundings, and measurements of cosmic radio-emission absorption at Vostok station (Antarctica) that the ionization of the lower ionosphere increases during low intensity of Forbush-type cosmic rays. This is manifested in increased absorption and the appearance of strong sporadic layers in the E-region.
Kozin, I. D.↗
The absorption of methane at low temperature in the 0.84 micron region
The absorption spectra of methane at low temperature with application to Jupiter atmospheric methane absorption is discussed. Experiments were made between 11,900 and 11950/cm. Attempts were made to observe single lines and determine the intensity of the spectra.
Hunt, R. H.↗
A survey of local interstellar hydrogen from OAO-2 observations of Lyman alpha absorption
The Wisconsin far ultraviolet spectrometer aboard OAO-2 observed the wavelength region near 1216 A for 69 stars of spectral type B2 or earlier. From the strength of the observed interstellar L sub alpha absorption, atomic hydrogen column densities were derived over distances averaging 300 pc away from the sun. The OAO data were compared to synthetic ultraviolet spectra, originally derived from earlier higher resolution rocket observations, which were computer processed to simulate the effects of absorption by different amounts of hydrogen followed by the instrumental blending.
Savage, B. D.↗
Sound propagation and absorption in foam - A distributed parameter model.
Liquid-base foams are highly effective sound absorbers. A better understanding of the mechanisms of sound absorption in foams was sought by exploration of a mathematical model of bubble pulsation and coupling and the development of a distributed-parameter mechanical analog. A solution by electric-circuit analogy was thus obtained and transmission-line theory was used to relate the physical properties of the foams to the characteristic impedance and propagation constants of the analog transmission line. Comparison of measured physical properties of the foam with values obtained from measured acoustic impedance and propagation constants and the transmission-line theory showed good agreement. We may therefore conclude that the sound propagation and absorption mechanisms in foam are accurately described by the resonant response of individual bubbles coupled to neighboring bubbles.
Manson, L.↗
The physical properties of the absorption envelopes of two QSOs.
The wide absorption t roughs of certain resonance lines in the spectra of the QSOs PHL 5200 and RS 23 are produced by pure scattering and must therefore be compensated by an equal amount of emission. Analysis of the transfer of resonance-line radiation through a differentially expanding atmosphere shows that the absorption-emission profiles can be quantitatively understood on this basis.
Scargle, J. D.↗
Gamma-ray absorption for a beam model of NP0532.
The model involves an assessment of the effect of beaming as indicated by the pulsations themselves rather than by assuming gamma-ray absorption by interaction with an isotropic photon field. The chief absorption process to be taken into account is that of pair production in the intense photon field. Most important is the pair production in the intense photon field which occurs during the pulse.
Stecker, F. W.↗
A cavity type absorption cell for double resonance microwave spectroscopy.
Description of an experimental dual resonant cavity absorption cell for observing microwave spectroscopic double-resonance effects. The device is composed of two Fabry-Perot interferometers excited by independent microwave sources and mounted at right angles in a suitable vacuum enclosure. The pumping transition is modulated by one source and the modulation induced on the rf absorption in the orthogonal cavity is detected.
Lee, M. C.↗
Performance of absorptive liners in the presence of spinning modes.
Results of free field measurements of the absorption coefficient of fiberglass, which indicate that the material has a high coefficient over a broad frequency range with little angular dependence. This material is also a very effective duct liner and attenuates spinning modes more rapidly than plane waves. The resonant absorber tested exhibits a strong angular and frequency dependence of the absorption coefficient, is only a moderately effective duct liner for spinning modes, and produces no measurable attenuation for plane waves.
Mcdaniel, O. H.↗
Comparison of measured and theoretical inverse bremsstrahlung and photoionization absorption of infrared radiation in a H-He plasma.
The absorption coefficients of 1.15- and 3.39-micrometer radiation for a homogeneous H-He plasma have been measured in a temperature and electron density range where the major absorption mechanisms are electron-ion inverse bremsstrahlung and neutral-atom photoionization. Measurements were made behind both the incident and reflected shock waves in a driven tube by recording the laser intensity transmitted along the tube diameter as a function of time. The measured values compare well with those obtained from theoretical calculations for a gas in thermodynamic equilibrium.
Billman, K. W.↗
Vibrational relaxation of the bending mode of shock-heated CO2 by laser-absorption measurements.
Study of the vibrational relaxation characteristics of shock-heated CO2 using a tuned CO2 laser absorption technique. Absorption-coefficient histories were obtained for a single rotational state in each of the -10 0- and -02 0- levels over the temperature range from 500 to 2000 K, and for 21 rotational states of the -10 0- level at 1000 K. These histories have been combined with translational-rotational temperature histories based on interferometer measurements to calculate vibrational relaxation times for the bending mode. The results verify the mutual equilibrium of the bending and symmetric-stretch modes due to Fermi resonance. The bending mode relaxation times are approximately 10% shorter than predicted from interferometer results using the ratio of specific heats. Furthermore, relaxation times based on measurements of different rotational states at 1000 K show a variation with quantum number J, indicating a possible rotational nonequilibrium during the vibration relaxation process.
Eckstrom, D. J.↗
The use of infrared absorption to determine density of liquid hydrogen.
Experimental evaluation of the use of infrared absorption for determining the density of liquid hydrogen, and discussion of the feasibility of an airborne densitometer based on this concept. The results indicate that infrared absorption of liquid hydrogen is highly sensitive to the density of hydrogen, and, under the operating limitations of the equipment and experimental techniques used, the determined values proved to be repeatable to an accuracy of 2.7%. The desiderata and limitations of an in-flight density-determining device are outlined, and some of the feasibility problems are defined.
Unland, H. D.↗