Classical trajectory calculations have been performed to determine the reaction rate constants and NO final vibrational‐rotational distributions of the N(4S) + O2 reaction at hyperthermal translational energies. The reaction occurs on two electronic potential energy surfaces, both of which must be considered for a realistic description of the N(4S) + O2 dynamics. The calculations, which are in good agreement with the available experimental data, show that the reaction has a very strong translational energy dependence and produces NO with extensive vibrational and rotational excitation. The present study provides the N(4S) + O2 reaction attributes necessary to predict NO formation and emission from translationally hot N(4S) in the thermosphere.

Global observations of the airglow, aurora, and solar scatter radiance of the earth's atmosphere have been made in the 1100-to 2900-/• wavelength region. The spectrometer and photometer utilized were pointed toward the earth center at all times on the polar-orbiting Department of Defense satellite S3-4. The experiment is described, and initial measurements are discussed. These measurements include detection of the nitrogen Lyman-Birge-Hopfield bands in the nightglow as well as in the dayglow. In addition, nitric oxide delta and gamma bands and oxygen Herzberg bands are found in the nightglow. VUV auroral enhancement and the tropical UV airglow due to atomic oxygen emission are also discussed. INTRODUCTIONThe Air Force Geophysics Laboratory has recently flown a satellite experiment which has made possible improved measurements of the ultraviolet radiation from the atmosphere as seen from space. This radiation consists of airglow, auroras, and scattered solar radiation. The spectral distribution, spatial characteristics, and radiance levels of this radiation are required for an understanding of the physical and chemical processes occurring throughout the atmosphere. This understanding will foster use of the ultraviolet wavelength region for applications such as remote s•ensing of atmospheric constituents or contaminants. The experiment made observations from the polar-orbiting Department of Defense (DOD) satellite S3-4, which was sta-The noise equivalent spectral radiance (NESR) of the spectrometer is obtained by multiplying the observed noise count per second by a radiance scaling factor measured in units of Rayleigh seconds/count, as given in Table la for a representative wavelength in the VUV and the UV range for 25-A bandwidth. The prefiight laboratory dark count rate was 0.6 and 0.8 c?s for the VUV and UV ranges, respectively. The dark count rate observed in flight outside polar regions is about 6 and 7 c?s for the VUV and UV ranges. The rate is up to 7 times higher at polar latitudes, indicating that the increase is due to energetic particles. When the radiance scaling factors from Table la are used, the flight NESR is between 0.11 and 0.8 R for 1216 A and between 0.2 and 1.4 R for 2500 A. bilized so that the line of sight was always pointing toward the The photometer is capable of obtaining atmospheric radiearth center, or nadir, direction. The wavelength region of ance in any one of five wavelength bands with any one of four 1100-2900 A was covered with a dual spectrometer. In addi-fields of view (FOV). It therefore has a large dynamic range tion, a photometer using a series of interference filters and apertures permitted coverage of four wavelength bands in the 1170-to 2000-/• region with high sensitivity and spatial resolution.This paper describes the experiment and initial results. Other aspects of this work will be described in future papers. EXPERIMENT Flight InstrumentsThe vacuum ultraviolet (VUV) background satellite experiment consists of a spectrometer, a photometer, and an electronics module. ...

Photoionization of the metastable Os (xzXg) molecule has been proposed as an important source of ionization in the D region. The wavelength region of interest is from 1027 to 1118 A, where ground state O• is the primary absorber of the incident solar flux but is not ionized itself. This paper presents improved ion production rates based on new laboratory data, including new O• (•zXg) photoionization cross sections and more detailed curves in several ground state O•. windows. Recent solar flux measurements reduce the continum intensity by about a factor of 5. This reduction is partly compensated by including in the calculations the Si III multipier, which is at the deepest O•. window (1108.2 A, minimum cross section _--4.4 X 10 -• cm •) and by the new ionization cross sections, which are generally larger than the previously assumed values. An important factor not previously considered is absorption by carbon dioxide, which has a much larger absorption cross section than ground state O•. throughout this region. The ground level mixing ratio has been assumed. The ion production rates are somewhat less than Hunten and McElroy's [1968] curves if CO• is not included. With CO•, a production rate of I ion cm -8 sec -1 is reached at approximately 80, 84, and 86 km for zenith angles of 0', 45', and 60', respectively. Hunten and McElroy find this rate to be 10 to 15 km lower. Concentrations of O_•* are calculated for a zenith angle of 45* for a variety of conditions, including a dry atmosphere and an atmosphere with 5 ppm I-I•O. Hunten and McElroy [1968] proposed photoionization of molecular oxygen in the metastable •A• state as an important source of O• * ions in the D region. This process was suggested after •A relatively large concentrations of O• • were detected in the upper atmosphere [Evans etal., 1968]. This ionization source could be important between 90 and 70 km, a region where the photoionization of NO by hydrogen Lyman a radiation has generally been considered the primary ionization process. It was previously noted that an additional ionization source was needed in this region to explain both the observed O• * and the total ion densities [Donahue, 1966]. The O•A• ionization could also be important at altitudes lower than 70 km in providing an O• • source capable of initiating a sequence of reactions leading to water vapor cluster ion formation [Ferguson and Fehsen[eld, •A A, which are the ionization thresholds of the O•Ag roetastable and the 02Z,-ground states, respectively. Shorter wavelength radiation is mainly absorbed by ground state 0•, which is the primary source of 0•* at higher altitudes. Since the photoionization rate calculations of Hunten and McElroy [1968] and Swider [1969], several of the input parameters have been improved. The OIA, ionization cross sections have been measured [Clarke and Wayne, 1970a, b], and we now present more detailed results. The solar flux has also been remeasured, leading to a significant decrease in the continuum region observed between strong lines [Hall and Hinteregger, 1...

Metastable resolved recombination, ionization and emission coefficients of impurity ions in thermal plasmas AIP Conf.The visible emission from electronically excited N02 has been studied both with thermal excitation in an electric oven and with recombination excitation from the nitric oxide-atomic oxygen reaction. In both cases the emission is continuous with weaker, diffuse bands superimposed. The correlation of these bands with N02 absorption bands has been extended. The thermal emission continuum begins near 3300 A and increases in intensity to the end of our range at 8600 A. The recombination emission continuum begins near 3800 A and has a broad maximum at 6200 A, in general agreement with previous workers. The absolute intensity of the thermal emission has been obtained at 100-A intervals between 4600 and 8600 A for temperatures between 972 and 1335°K. Excitation energies, which are obtained from the variation of intensity with temperature, range from 66 kcal at 4600 A to a minimum of 44±1 kcal near 8300 A. This latter value is Eo, the minimum energy of the emitting state of N02• Radiative lifetimes are obtained for thermal emission which range from 100 to 1 J.Lsec depending on emission wavelength and which approximately agree with fluorescent lifetimes for comparable excitation energies. The results are compared with shock tube measurements and are discussed in relation to air emissivity and opacity problems.If the choice is limited to quadratic forms, it is impossible to find representations of quantum states by positive distributions on phase space, either in the ordinary or in an extended "coarse-grained" sense.

The recent discovery of relatively large concentrations of O2(1At7) in the upper atmosphere had led to consideration of photoionization of this metastable molecule as a major source of 02 + in the D region. Our initial calculations indicated that this process was less important than previously believed, primarily because of COa absorption. In this paper we consider further the effect of various reasonable O•, CO•, and O•(lz¾) density profiles on the ion-production rates by this process. Within the limits described herein the ion-production rate (ion cm-3 sec -•) is approximated by the following function of Nor, the O• column density in molecules per square-centimeter column, and nla, the Oa(1/¾) density in molecules per cubic centimeter: P(O•.+) = nla [0.549 X 10 -ø exp (--2.406 X 10 -•'øNo2) q-2.614 X 10 -ø exp (--8.508 X 10-•'øNo2)]