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SHARDANAND

Publications and source records attributed to SHARDANAND.

14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Absolute Rayleigh scattering cross sections of gases and freons of stratospheric interest in the visible and ultraviolet regions

The laboratory measurements of absolute Rayleigh scattering cross sections as a function wavelength are reported for gas molecules He, Ne, Ar, N2, H2, O2, CO2, CH4 and for vapors of most commonly used freons CCl2F2, CBrF3, CF4, and CHClf2. These cross sections are determined from the measurements of photon scattering at an angle of 54 deg 44 min which yield the absolute values independent of the value of normal depolarization ratios. The present results show that in the spectral range 6943-3638A deg, the values of the Rayleigh scattering cross section can be extrapolated from one wavelength to the other using 1/lambda (4) law without knowing the values of the polarizabilities. However, such an extrapolation can not be done in the region of shorter wavelengths.

SHARDANAND↗
NASA NTRS1977

Collision-induced absorption of O2 in the Herzberg continuum

Using a one meter normal incidence grating monochromator, the total absorption of radiation for O2 has been reinvestigated between 2000-2500 A. The absorption cross sections of O2 and O4 are then derived from total absorption measurements and compared with other available data. Additional measurements of O2 absorption have been made in the presence of Ar which does not absorb in this spectral region and is chemically inactive with O2. It is found that the absorption of oxygen increases in the presence of Ar, which is interpreted as due to the formation of O2-Ar dimers.

SHARDANAND↗
NASA NTRS1975

Free radical OH, a molecule of astrophysical and aeronomic interest

The chemistry and physics of the gaseous OH free radical as it applies to interstellar space, planetary atmospheres, and the sun is presented. Topics considered are: (1) rotational-vibrational transitions; (2) dissociation and ionization processes; (3) spectral characteristics.

Mohan, H.↗
NASA NTRS1973

On the measurement of Rayleigh scattering by gases at 6328A

The problem of laboratory measurements of Rayleigh scattering and depolarization ratio for atoms and molecules in the gaseous state is described. It is shown that, if the scattered radiation measurements are made at two angles, the normal depolarization ratio cannot be determined meaningfully. However, from scattering measurements, the Rayleigh scattering cross sections can be determined accurately. The measurements of Raleigh scattering from He, H2, Ar, O2, and N2 for unpolarized radiation at 6328A are reported and compared with similar measurements at 6943 and 1215.7A.

SHARDANAND↗
NASA NTRS1972

Problem of photochemical equilibrium of ozone in planetary atmospheres: Ozone distribution in the lower atmosphere of Mars

The inherent errors of applying terrestrial atmospheric ozone distribution studies to the atmosphere of other planets are discussed. Limitations associated with some of the earlier treatments of photochemical equilibrium distributions of ozone in planetary atmospheres are described. A technique having more universal application is presented. Ozone concentration profiles for the Martian atmosphere based on the results of the Mariner 4 radio occultation experiment and the more recent results with Mariner 6 and Mariner 7 have been calculated using this approach.

Grams, G. W.↗
NASA NTRS1972

Compact photomultiplier housing with controlled cooling.

Description of a compact photomultiplier housing which can provide controlled cooling to the photomultiplier tube down to -90 C. The cooling is accomplished by flowing liquid nitrogen cooled helium gas through a series of coils which envelop the photocathode portion of the tube. The temperature is controlled by controlling the flow of the gas with a fine adjustable needle valve. The temperature is measured near the photocathode of the photomultiplier by a calibrated thermistor.

SHARDANAND↗