Computed and observed cyanide-radical spectra of three N stars in the infrared
N stars Y CVn, RY Dra and 19 Psc IR synthetic cyanide radical spectrum analysis, determining C 12/C 13 ratio
Fay, T. D., Jr.↗
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Perturbation analysis and constants for the red system of the cyanide radical
CN radical red system molecular constants, considering degenerate perturbation effects in shifts between electronic states
Fay, T.↗
Formation of free radicals during mechanical degradation of elastomers.
Solithane 113 (an amorphous polyurethane elastomer) was prepared by curing equal proportions of castor oil and trifunctional isocyanate for 6 hr 45 min at 170 F. The sample material was mechanically degraded by grinding below and above its glass transition point at liquid nitrogen and room temperatures. The EPR spectra of ground samples were recorded and the number of free radicals were determined by a computer double-integration of the recorded spectra and by a comparison of the values with those of a standard material. Curves of EPR spectra suggest that different molecular mechanisms may be active in degradation of this material below and above its glass transition temperature.
Devries, K. L.↗
Quenching of the B /super 2/Sigma-plus state of the CN radical.
The quenching of the B (super 2)Sigma-plus fluorescence from the CN radical has been studied as a function of the relative velocity of the quenching collision and the total pressure in the fluorescence cell. The rate constant for the quenching of the CN fragment by ICN vapor was found to be directly proportional to the relative velocity of the quenching collision. Electronic quenching was also observed for methane, diatomic hydrogen, Kr, and Ar.
Jackson, W. M.↗
Are HO radicals produced in the reaction of O(3P) with 1-C4H8 ?
The reaction of O(3P) with 1-C4H8 was examined in the presence of CO which scavenges HO radicals to produce CO2. From the CO2 quantum yield, an upper limit to the efficiency of HO production in the reaction of O(3P) with 1-C4H8 was found to be 0.020 at both 298 and 473 K.
Luria, M.↗
Rate constants for the reactions of hydroxyl and hydroperoxyl radicals with ozone.
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.
Demore, W. B.↗
Stabilities of nitrogen containing heterocyclic radicals and geometrical influences on non-radiative processes in organic molecules
Theoretical and experimental work on generating radicals by removal of a hydrogen atom from pyrrole, imidazole, indole, and carbazole is reported. Photophysical studies on indolizine and related aza-derivatives show that materials having large S2-S1 energy gaps might exhibit upper state fluorescence. Photodecomposition quantum yields of a series of sterically hindered p-aminobenzene diazonium cations in water were found structurally and wavelength dependent and unquenched in aqueous sodium bromide solutions. Photodecomposition of diazonium materials did not produce a metastable species with a longer lifetime than 1 msec.
Evleth, E. M.↗
Optical measurement of static temperature and hydroxyl radical profiles in a hydrogen-fueled supersonic combustor
Profiles of static temperature and hydroxyl radical concentration were measured in a two-dimensional supersonic combustor test section 22.8 cm downstream of hydrogen injection. A high-pressure gas generator supplied vitiated air to the test section at Mach 2.44, atmospheric pressure, and a total temperature of about 2240 K. Room-temperature hydrogen was injected through a 0.40-cm step slot at Mach 1 and matched pressure. The measurements utilized a noninterfering spectral line absorption technique in which narrow ultraviolet emission lines of the hydroxyl electronic transition are absorbed by the broader absorption lines in the combustion gas. Comparison of the measured temperature profiles with theoretical calculations showed good agreement.
Gaugler, R. E.↗
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.↗
The ethynyl radical C2H - A new interstellar molecule
Four new interstellar lines have been detected near 87.3 GHz. Based on laboratory ESR data these lines have been positively defined as hyperfine components of the lowest rotational transition of the ethynyl radical C2H. The observations gave precise values for the C2H rotation, spin-doubling, and hyperfine constants. C2H is probably one of the most abundant interstellar polyatomic molecules yet detected.
Tucker, K. D.↗
Theoretical description of the 2A/double prime/ and 2A/prime/ states of the peroxyformyl radical
Simple orbital ideas are used to describe the lowest two states of the peroxyformyl radical, and ab initio Hartree-Fock calculations in these states are reported. It is found that both states may be formed exothermically by association of O2 and HCO in their ground states; however, the excited state may decompose readily to OH and CO2. The possible role of such processes in oxidation of aldelydes is discussed.
Winter, N. W.↗
Investigations of the inhibitory effects of tocopherol (vitamin E) on free radical deterioration of cellular membranes
The inhibitory effects are investigated of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate on the free radical deterioration of cellular membranes. The level of toxicity of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate in mice is determined.
Richardson, D.↗
Radical simplification made easy
Problems encountered in manipulating algebraic numbers and functions are discussed. Methods for simplifying nested and un-nested radicals are described. Results obtained are either classical or direct corollaries of classical results.
Zippel, R. E. B.↗
Atomic chlorine and the chlorine monoxide radical in the stratosphere - Three in situ observations
Three simultaneous observations of atomic chlorine (Cl) and the clorine monoxide radical (ClO) are reported which encompass the altitude interval between 25 and 45 kilometers. Together, Cl and ClO form a gas-phase catalytic cycle potentially capable of depleting stratospheric ozone. Observed Cl and ClO densities, although variable, imply that chlorine compounds constitute an important part of the stratospheric ozone budget. The results are compared with recent models of stratospheric photochemistry which have been used as a basis for predicting ozone depletion resulting from fluorocarbon release.
Anderson, J. G.↗
Detection of the C4H radical toward IRC plus 10216
Four emission doublets in the millimeter-wave spectrum of IRC plus 10216 are identified as successive rotational transitions of the linear butadiynyl radical (C4H). The identifications are made on the basis of the agreement to within about 1 part in 1000 between the observed rotation constant of C4H and the value obtained from a Hartree-Fock calculation. A rough estimate of the amounts of C4H and C3N in the molecular envelope of IRC plus 10216 is given. The results indicate that C4H seems to be the more abundant species by about a factor of 4.
Guelin, M.↗
Improved apparatus for trapped radical and other studies down to 1.5 K
A Dewar system and associated equipment for electron paramagnetic resonance (EPR) studies of trapped free radicals and other optical or irradiation experiments are described. The apparatus is capable of reaching a temperature of 1.5 K and transporting on the order of 20 W per K temperature gradient; its principal advantages are for use at pumped cryogen temperatures and for experiments with large heat inputs. Two versions of the apparatus are discussed, one of which is designed for EPR in a rectangular cavity operating in a TE(102) mode and another in which EPR is performed in a cylindrical microwave cavity.
Woollam, J. A.↗
Boundary layer measurements of the OH radical in the vicinity of an isolated power plant plume - SO2 and NO2 chemical conversion times
Direct measurements of the OH radical in the vicinity of an isolated power plant plume are reported. These measurements were used to estimate the conversion time of SO2 to H2SO4-sulfate aerosol via the initiating step OH + SO2 + M yields HSO3. Using the near-high-noon measured value of OH (9.5 million per cu cm), resulted in a 1/e conversion time of 1.4 days. The latter lifetime would correspond to a conversion rate of about 2%/hr. When the lifetime calculation was modified to take into consideration the OH diurnal cycle, the 1/e conversion time for SO2 was found to be 4.4 days, giving an apparent overall rate of conversion of about 0.7%/hr. Similar calculations carried out for the conversion of NO2 to NHO3 resulted in 1/e lifetimes for NO2 of 2-3 h for midday time periods.
Davis, D. D.↗
Measurement of hydroxyl radical in the upper atmosphere using lidar from the Space Shuttle
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.
Heaps, W. S.↗