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Stirred reactor-mass spectrometric technique to determine rate constants and activation energies of carbon monoxide reactions with hydroxyl radicals and oxygen atoms
Hydroxyl radical emission, hypotheses attempting to explain OH emission origin, including possible maser mechanism and interstellar communications
Hydroxyl radical radio spectral line emission from IR stars detected by radio telescope
Spectrometric analysis on space-time properties of hydroxyl emission in various regions of sky
Intensity and rotational temperature of hydroxyl emission at high latitudes during winter
Effects of solar cycle on hydroxyl emission from upper atmosphere
Reagent menthyl chloroformate use in optical analysis of asymmetric amino and hydroxyl compounds by gas chromatography
Time of flight mass spectrometric technique for measuring rate constants of hydroxyl radical reactions with hydrogen and carbon monoxide
Airborne photometer instrumentation and measurement data on high latitude hydroxyl airglow emission
Ground and airborne hydroxyl emission observations were made in the northern polar regions. The ground observations were made at Ester Dome, Alaska, and the airborne observations were made during the 1969 NASA Airborne Expedition. The analysis of some of the data that were acquired has lead to the following conclusions: (1) Airglow OH measurements show no appreciable change with latitude or longitude. (2) Diurnal changes at northern latitudes are similar to those observed in midlatitude regions. (3) Two types of OH enhancements were observed photometrically in the 9370 A region - one associated with visible aurora, and the other uncorrelated with visible aurora. High resolution spectra under both inactive and active conditions indicate that the OH enhancements seen photometrically in active aurorae are probably due to contamination of the filter pass bands by the unexpected enhancement of the NI multiplet lines at 9387 A and 9393 A. All previously reported aurorally associated enhancements are consequently suspect.
Chain decomposition of ozone by hydroxyl and hydroperoxyl radicals has been observed. The rate constant at 300 K for OH + O3 yielding HO2 + O2 is eight times ten to the -14th power cubic centimeters per second. The rate constant for HO2 + O3 yielding OH + 2O2 is three times ten to the -15th power cubic centimeters per second. These results have implications concerning stratospheric ozone.
Observations of hydroxyl (OH) emission from Comet Kohoutek were made during the evening of 24 January 1974, from an altitude of 41,000 feet. The comet, of visual magnitude 5.5 at the time of observation, was photographed with an f/1.3 Maksutov slitless spectrograph of 150-mm aperture. This spectrograph used a double quartz prism as the dispersion element to isolate the OH radiation in the low-resolution spectrum. A nearly spherical coma of OH about three arc minutes diameter, as observed from an earth-comet distance of 0.88 AV, was photographed. The OH emission was the strongest feature in the spectrum and produced an irradiance of 3 billionths erg per sq cm per sec at the earth.
Quantitative values were computed which show the effects of the presence of small amounts of oxygen, hydrogen, and hydroxyl radicals on the finite-rate chemical kinetics of premixed hydrogen-air mixtures undergoing isobaric autoignition and combustion. The free radicals were considered to be initially present in hydrogen-air mixtures at equivalence ratios of 0.2, 0.6, 1.0, and 1.2. Initial mixture temperatures were 1100 K, 1200 K, and 1500 K, and pressures were 0.5, 1.0, 2.0, and 4.0 atm. Of the radicals investigated, atomic oxygen was found to be the most effective for reducing induction time, defined as the time to 5 percent of the total combustion temperature rise. The reaction time, the time between 5 percent and 95 percent of the temperature rise, is not decreased by the presence of free radicals in the initial hydrogen-air mixture. Fuel additives which yield free radicals might be used to effect a compact supersonic combustor design for efficient operation in an otherwise reaction-limited combustion regime.
The vibrational energy distributions of hydroxyl molecules in the lower atmosphere were calculated. As expected, the distributions are found to be highly nonequilibrated. Attention is drawn to the role that vibrationally-excited molecules may play in modifying the chemistry of the lower atmosphere. The most likely role for the OH molecule in the stratosphere is via reactions that may not otherwise be energetically viable.
The paper examines the measurements of hydroxyl radical in the upper atmosphere using lidar from the Space Shuttle. The measurement of the latitudinal and diurnal variation of OH would provide tests for stratospheric and mesospheric chemistry; two lidar systems aboard the Space Shuttle are described with the first providing the best signal to noise ratio for nighttime measurements at altitudes above 40 km, and the second giving a better performance during the day and at lower altitudes.
Behavior of the hydroxyl radical produced by the photolysis of water vapor in the earth's early atmosphere is examined. Because of the substantial OH radical reactivity with trace species (CO, HCl, SO2, H2S, NH3, and CH4) the formation of molecular oxygen may be prevented, even at a trace species mixing ratio. The photolysis rate of H2O, with corrections for hydrogen exospheric escape, is capable of describing the oxidation of the atmosphere and crust but may not be used to determine the rate of molecular oxygen generation without consideration of the various OH-trace species reactions.
The hydroxyl temperatures in the upper atmosphere were measured over a five-week period in January and February of 1975 and 1976 in order to determine the variation of the rotational temperatures of OH with stratospheric warming events occurring over the New England area. The OH temperatures were also recorded during the summer of 1975 in the Fairfield, Connecticut area. Data show a wide fluctuation in temperatures amounting to as much as a couple of hundred degrees in the course of an evening. A modified Ebert-Fastie spectrometer with a focal length of 1 meter was used to examined the vibration-rotation bands of atmospheric OH in the 7000 to 9000 range. This wavelength was searched and the strongest signal was obtained from the 6-2 band (band head at 8280 A). Graphs show the 6-2 band of the Meinel OH spectrum, the real time and average spectra for the 6-2 band of OH, and rotational temperature of OH vs time for two evenings.
The rate constant for the reaction of hydroxyl radicals with nitric acid in the 225-443 K temperature range has been measured by means of the flash photolysis resonance fluorescence technique. Above 300 K, the rate constant levels off in a way that can only be explained by the occurrence of two reaction channels, of which one, operative at low temperatures, proceeds through the formation of an adduct intermediate. The implications of these rate constant values for stratospheric reaction constants is discussed.