Engineering topics
Publications and source records attributed to Williams, D..
Previous research dealing with telluric gases is briefly reviewed. Current research concerning absorption-line broadening, and particulate constituents of planetary atmospheres are discussed. Two articles are included: optical constants of liquid ammonia in the infrared, and broadening of infrared absorption lines at reduced temperatures for nitrous oxide.
Measurement of the normal-incidence spectral reflectance of water at 5, 27, and 70 C in the spectral region between 5000 and 350 per cm. From the measured values of spectral reflectance the optical constants n sub r and n sub i are determined by Kramers-Kronig methods. The band strengths and bandwidths have been determined for the absorption bands near 3400, 1640, and 600 per cm at each temperature. A similar study of deuterium oxide at 27 C has been conducted for purposes of comparison.
The initial stages of the research were involved with a test of Burch's law of multiplicative transmittance for mixed absorbing gases when their lines are broadened by H2 and He, which are constituents of the atmospheres of the major planets. The broadening of individual lines in the CO fundamental by various gases was investigated. Line strength and half-width for individual CO lines were studied as a function of temperature. Measurements of total band absorptance as a function of absorber thickness and total effective pressure were made at various temperatures for bands of CO and N2O. Attempts were made to develop a phenomenological theory of line broadening that would account for the phenomena observed for the CO fundamental and those reported for more highly polar gases. Laboratory measurements of nitric acid vapor absorptance were compared with balloon measurements in arriving at an estimate of the quantity of nitric acid vapor present in the earth's atmosphere in the region of the ozone layer.
A knowledge of the complex dielectric constant of soils is essential in the interpretation of microwave airborne radiometer data of the earth's surface. Measurements were made at 37 GHz on various soils from the Phoenix, Ariz., area. Extensive data have been obtained for dry soil and soil with water content in the range from 0.6 to 35 percent by dry weight. Measurements were made in a two arm microwave bridge and results were corrected for reflections at the sample interfaces by solution of the parallel dielectric plate problem. The maximum dielectric constants are about a factor of 3 lower than those reported for similar soils at X-band frequencies.
The strengths of the rotational lines in the R branch of the CO fundamental have been determined at temperatures of 298, 202, and 132 K by means of a high-resolution spectrograph. The results can be used to determine line strengths at other temperatures by means of the Herman-Wallis relation or by considerations of the populations of the rotational levels in the ground vibrational state. Parameters describing the self-broadening and carbon dioxide broadening of CO lines have been determined at 298 and 202 K. The results are compared with other recent experimental and theoretical studies.
We have measured the foreign-gas broadening coefficients for collisional broadening of lines in the nu-3 fundamental of N2O by He, Ne, Ar, Kr, Xe, H2, D2, and CH4. These coefficients, which give the ratio of the line-broadening ability of these gases to the line-broadening ability of N2, can be used with recent measurements and calculations of N2 broadening to obtain optical collision cross sections.
An evacuated high-resolution Czerny-Turner spectrograph, which is described in this paper, has been used to determine the strengths S and self-broadening parameters for lines in the R branch of the nu (sub 3) fundamental of carbon dioxide at 298 and at 207 K. The values of self-broadening parameters at 207 K are greater than those to be expected on the basis of a fixed collision cross section.
The broadening of individual lines in the CO fundamental by various gases has been investigated. The results indicate that the ratio of the self-broadening ability of CO to the line-broadening ability of foreign gases is greater for lines in the band wings than for lines near the band center when the molecular mass of the broadener is less than that of CO. The results have been interpreted in terms of a phenomenological theory. Studies of the relative line broadening abilities of foreign gases have provided information that can be used to provide optical collision cross sections for individual lines in the CO fundamental.
Collisional broadening of IR absorption lines in vibration-rotation bands of carbon monoxide and hydrochloric acid
Collisional broadening of infrared absorption lines with application to planetary atmospheres
Nitric acid vapor in atmosphere as function of altitude from spectrograph, predicting downward diffusion
IR absorptance of CO below room temperature, determining strength and half widths of lines in R branch of fundamental band
Collision cross sections compared for line broadening in R branch of CO fundamental
Collisional line broadening ability of various foreign gases relative to nitrogen for rotational lines in fundamental absorption band of carbon monoxide
Infrared spectroscopy of gases used to simulate planetary atmospheres
Spectral transmittance of mixture of carbon monoxide and nitrous oxide for overlapping absorption bands
Computer under control of the flo-tran program automatically produces and updates flowcharts of fortran program source decks fed to it. The flowcharts are produced on either 35mm film or paper.