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Expressions for differential and total cross sections for atom-diatom scattering are derived using the impulse formalism without any approximations. Results for the rotational-vibrational scattering are obtained without using the peaking approximation (PA). For the specific case of a hard-core potential, it is shown that, except for elastic scattering, PA results are substantially different from the true impulse results.

Measurement of emission from the Earth's atmosphere in the far infrared due to transitions between fine structure levels of the ground state ( 3 P) of atomic oxygen at 63 μm ( 3 P 1 → 3 P 2 ) and 147 μm ( 3 P 0 → 3 P 1 ) is proposed. These magnetic-dipole allowed transitions with long radiative lifetimes (∼ 3.2 h for the 63 μm transition and ∼ 16.3 h for the 147 μm transition) are assumed to be in equilibrium with the local translational temperature. A one-dimensional onion-peel inversion of the limb emissions at 63 and 147 μm from a model atmosphere is shown to yield reasonable results for both the temperature and atomic oxygen density in the 90–250 km altitude range.

Large enhancements in the 4.3 micron infrared radiance have been observed since the early 1970's. Auroral photochemical models predict large enhancements in the populations of NO+(ν) and CO2 v3 that radiate in the 4.3 micron region. The strong 4.26 micron band of 12C16O2 is largely self-absorbed in the 90–110 km region with limb-viewing line-of-sight (LOS) optical depths at line center approaching 1000. Line-by-line calculations of the 626 isotope (001-000) transition and weak bands (636, 627, 628, and the 626 011-010 hot band) are necessary in order to calculate accurate limb spectra. The large effect of radiative transfer of the CO2 lines means that their contribution to the limb spectra compared to that of the optically thin NO+(Δν=1) lines is a sensitive function of the geometry of the auroral arc along the LOS.

A preliminary analysis of high-resolution infrared spectra of the aurorally dosed lower thermosphere above Poker Flat Research Range (PFRR), Alaska, obtained by an uplooking cryogenic field-widened interferometer (FWI) is presented. Both models and spectral-fitting/resolution-enhancement methods are used to discuss the behavior of NO, CO, NO + , and CO 2 v 3 vibrational bands in the high-latitude thermosphere.

It is proposed to measure the line intensities and profiles of the 63um 3 P 1 − 3 P 2 transition and 147um 3 P 0 − 3 P 1 transition of the ground electronic state of atomic oxygen from a space-borne platform in a limb-viewing mode. The temperature and atomic oxygen density can be obtained by inversion from the total radiances in the two channels. The line profiles provide a confirmation of temperature and, in addition, yield the component of the wind speed along the line-of-sight. In the optically thick regime (below tangent height

Emission line shapes are calculated numerically for isolated optically thick infrared lines in the earthlimb as a function of tangent height using a general nonlocal thermodynamic equilibrium (non-LTE), upper-atmospheric line-by-line radiation transport code. It is shown that the exact integral form of the transport equation can be written in a form that is easily amenable to analytical approximation of high accuracy. In this form, the limb spectral radiance Iv appears as a weighted average of nu/nl, the ratio of upper-state to lower-state population density, multiplied by the absorptivity 1 - exp[-τ(v)], where τ(v) is the total optical path along the line of sight. In the wings the variation of Iv is governed by the absorptivity; in the core of the optically thick line, Iv is determined by the averaged population ratio. The analytical forms enable us to calculate all of the important features of the self-absorbed line and agree remarkably well with more time-intensive numerical calculation. These results are illustrated by calculations on the 15-μm CO2 v2 (0110-0000) vibrational transition for tangent heights ranging through the mesosphere and lower thermosphere. Even though the collision linewidth is less than 1% of the Doppler width at these altitudes, it is shown that it is essential to use the Voigt line profile in this calculation rather than the Doppler profile. Failure to do so leads to a total band radiance that is in error by up to a factor of three, as well as incorrect band shapes and line shapes.

A hopping model for excitons is used to calculate the rate constant for electron—hole production due to exciton—exciton collision annihilation. The value for the rate constant obtained using a more recent value for the conduction‐band edge and better orthogonalization scheme is 3.0×10−11 cm3 sec−1. This is an order of magnitude greater than the value 2.5×10−12 cm3 sec−1 obtained by Choi and Rice using the coherent model. The only experimental measurement is by Silver, Olness, Swicord, and Jarnagin which gives 5×10−12 cm3 sec−1 for the rate constant.

Laser‐excited vibrational fluorescence measurements have given rates for nearly resonant vibrational energy exchange between HCl and D2 molecules over the temperature range of 196–343°K. The energy transfer cross section σν ν shows an inverse temperature dependence; namely, decreases as temperature increases. The magnitude and temperature dependence of these cross sections could be fit by first order calculations based on quadrupole‐quadrupole, and dipole‐quadrupole interactions. The rates of vibrational deactivation of HCl by He were found to increase with temperature. However, the results on HCl self‐relaxation also show an inverse temperature dependence over this temperature range studied. This enhancement observed at lower temperature is probably caused by the attractive chemical forces exerted between HCl molecules.

The Schumann–Runge band system of O2 involving transitions between the X 3Σg− ground state and the B 3Σu− excited state has been the subject of many investigations which have shown that the radiating state is strongly coupled to the O atoms and that the population mechanism is very fast. In the present study, the emitted radiation was monitored with filter–photomultiplier combinations as a function of time behind incident shock waves in O2, O2–Ar, and O2–Ne mixtures at wavelengths centered at 2300 and 3250 A. Initial pressures in the shock tube were 1–100 torr and the (equilibrium) temperature range was 2800–5300°K. The radiation, subsequent to a short incubation time, rose monotonically to a plateau level given for each of the two channels by I2300 = 4.4 × 10−36[exp(− 20.3 × 103 / T)](O)2 and I3250 = 1.1 × 10−36[exp(− 11.3 × 103 / T)](O)2 in watts/cubic centimeters·steradians·microns where (O) is the number of O atoms per cubic centimeter. These results are in disagreement with the results of Myers and B...

A simple model is developed for a collision pair consisting of a polar diatomic molecule and a perturbing inert gas atom. The effects of long‐range forces arising from the dipole and quadrupole moments of the polar molecule on its rotation—vibration spectrum are considered. Detailed calculations are carried out to obtain the integrated intensities of the induced Q branches and the rotational line shifts in the spectra of HCl— and HBr—inert gas mixtures. The calculated results for both phenomena agree in magnitude with the experimental data without the use of adjustable parameters. The results are also consistent with the observed temperature dependences of the Q‐branch intensities. In its present form the theory is unable to reproduce quantitatively either the fine structure of the Q branch or the J dependence of the line shifts.

The cross section for the photoionization of the anthracene molecule has been calculated. It is shown that the main contribution to the cross section at the threshold arises from the orthogonalized part of the orthogonal plane wave used as a wavefunction for the free electrons. The emission of electrons is shown to be highly anisotropic. Combined with further experimental work on intrinsic photoconduction, the calculations have the potential of determining the conduction band edge.

Linear least-squares methods and the Jansson method of constrained nonlinear spectral deconvolution were used to analyze atomspheric emission spectra obtained in the Field-Widened Interferometer (FWI) experiment. The analysis provides estimates of line intensities and spectra of enhanced resolution. A conclusion of the study is that NO+ was not present in the auroral event observed by the FWI. Keywords: Interferometer data; Least-squares analysis; Spectral deconvolution; Infrared; atmospheric emission; Carbon dioxide; Nitrogen oxides.

We present an analysis of high-resolution (1.2-cm-1) zenith-looking spectra of the 4.3-µm region arising from the aurorally dosed lower thermosphere (90–125km). These were obtained by a cryogenic field-widened interferometer (FWI) launched from Poker Flat, Alaska, in April 1983. We compare the spectra with model results from our infrared auroral model AARC. This code includes time-dependent excitation of five CO2 v 3 bands, via vibrational energy transfer from N2(v), and prompt auroral excitation of NO+(v), via fast chemi-luminescent ion-molecule reactions. We use ground-based photometer data to estimate the auroral predosing, but must make assumptions about the hardness of the electron flux responsible for the predosing. A line-by-line radiation transport code is used to calculate the radiance in the optically thick CO2 lines. The modeled bandshape is then compared to the measured spectra below 100km, where the radiation becomes optically thick. The modeled spectrum is very sensitive to the altitude profile of excitation in the optically thick region. Thus the detailed ionization profile below the altitude of peak deposition is very important, but this profile is very difficult to determine with sufficient accuracy. Fairly good agreement is obtained between data and model, with the exception of notable departures below the dosing peak. Finally, we draw some conclusion about our ability to model quantitatively such optically thick emissions and suggest planned improvements in our models.

The fluorescence decay curves of Bergman, Levine, and Jortner are interpreted in terms of autoionization. It is shown that autoionization is always more important than collision ionization of excitons located on different sites.

Calculations using the theory of the pressure‐induced Q branch in the 1Σ polar molecules proposed in an earlier article are brought up to date in view of the recent developments. Experiments are suggested which may give the values of the molecular quadrupole moment and its first derivative, evaluated at equilibrium internuclear distance, with c.m. of the molecule as origin.

In this paper we analyze daylight 1.58-µm limb radiance profiles obtained by the Spectral Infrared Rocket Experiment (SPIRE) in the 40- to 70-km tangent height region, near the dawn terminator. Photochemical model calculations indicate that the O2(a¹Δg, υ = 0) → O2(X³Σg−, υ = 1) transition provides the necessary radiance if we choose the Einstein coefficient for the (0, 1) transition, A(0, 1) = 5.0×10−6 s−1. This value is within the range of past field and laboratory measurements but 3 times larger than what the Franck-Condon principle would predict assuming the accepted value of 2.58×104 s−1 for A(0, 0). One-dimensional inversions of the radiance give reasonable profiles of O2(¹Δg) for altitudes above the radiance peak. Using the best fit values for A(0, 1), a two-dimensional model treatment can give good agreement to the limb radiance even below the radiance peak, but there is not enough information in the limb radiance scans to do a two-dimensional inversion. The two-dimensional simulation of the limb radiance is more successful since it takes into account the change in the O2 singlet delta density with solar zenith angle and not just altitude, and because the direct calculation avoids the numerical error that accumulates in the one-dimensional inversion especially below the radiance peak.

A recursive algorithm was developed to invert spectrally resolved earth limb radiance profiles representing the non-local thermodynamic equilibrium altitude regime and species/tangent heights that are optically thin. It was used to infer vertical distributions of temperature and excited NO density from data measured by the Spectral Infrared Rocket Experiment in the NO fundamental band near 5.3 µm. The solution for excited NO density was used to compute atmospheric cooling rates for the 5.3-µm band and the de-excitation rate constant ko for the reaction NO* + O → NO + O.

A detailed study of the vibrational states of CO2 in the upper atmosphere was conducted in order to enable the calculation of emission near 2.7 µm expected for sunlit conditions. New line-by-line computer codes were used to evaluate the solar pumping of vibrational levels and to calculate the limb radiance. Excitation and quenching mechanisms are quantified and compared for several important vibrational states in the altitude range 40–110 km. The dominance of fluorescent CO2 hot band emission for altitudes below 75 km is confirmed. The spectral distribution, and to a lesser degree the total band radiance, are shown to be very sensitive to collisional interactions. Detailed results are presented and compared with experiment.

A Spectral Infrared Rocket Experiment was launched from Poker Flat, Alaska, on September 28, 1977, to measure infrared emission spectra from the earth limb atmosphere. Spectrometers measured emission spectra from 1.40 to 16.5 µm during 12 vertical scans of the limb region (tangent heights 0 to 250 km) traversing the night, terminator, and day sectors of the limb atmosphere. The spectrometers were cryogenically cooled and telescoped for out-of-field rejection of the more intense radiation from lower altitudes. High-quality spectra were obtained with clearly identifiable features of CO2, O3, NO, OH, H2O, NO2, HNO3, and O2, as well as Rayleigh scattering. Spectra and tangent height emission profiles of selected species are presented and compared with theoretical emission models including those of Degges and Smith (Limb Model) and LOWTRAN 4. The salient findings are as follows: At a height of 80 km, CO2 daytime emission from fluorescence around 4.3 µm was almost 2 orders of magnitude greater than the nighttime emission. At 15 µm the CO2 radiance profiles showed little day-night differences but exhibited an unexpected radiance plateau between 95 and 110 km. The ozone peak radiance at 9.6 µm (ν3) showed order of magnitude day-night differences above 70 km tangent height showing a decrease in concentration of O3 during daytime due to photodissociation. The observed radiance in the 9- to 12-µm wavelength region exhibited evidence of chemiluminescent emission from hot bands of O3. NO (Δυ = 1) peak radiance at 5.3 µm, due to O atom excitation, is a broad maximum at 120 km tangent height. The nighttime OH fundamental (Δυ = 1) and overtone (Δυ = 2) emissions showed extensive radiation from higher vibrational levels. The daytime 2.7-µm fluorescent radiation was composed of emission from both H2O and CO2. Emission from NO2 at 6.15 µm (ν3) was observed at night only but was clearly identifiable amid the H2O (ν2) spectrum. Measured radiation in the 6.3-µm vibrational band of water vapor at 60 and 70 km agrees with the Air Force Geophysics Laboratory non-local thermodynamic equilibrium Limb Model using mixing ratios of 5 and 1.5 parts per million by volume, respectively. The radiance from O2 (a¹Δg) at 1.58 µm was observable from tangent heights of 30 to 80 km in the daytime only and shows a critical dependence upon the solar elevation angle. As expected, Rayleigh scattering was the dominant daytime source of radiation between 1 and 3 µm in the limb atmosphere for tangent heights of up to 40 km.

Spectrally resolved earth limb radiance profiles were inverted to recover concentration and temperature profiles in the non-LTE altitude regime. These simulations used synthetic spectra for the optically thin NO fundamental band near 5.3 μm. The purpose of the study was to test a nonlinear inversion algorithm used previously to invert real data obtained in the Spectral Infrared Rocket Experiment. Specifically, the tests consisted of attempts to retrieve singly and doubly peaked excited density vs altitude profiles and kinetic temperature vs altitude from the synthetic spectral data with and without added noise. A nonlinear inversion algorithm was used rather than the formal inverse of the Abel integral equation because it offers promise for species/bands that are not optically thin.