Contamination of ground-based measurements of OI (6300 Å) and NI (5200 Å) airglow by OH emissions     

R.G. Burnside  J.W. Meriwether  M.R. Torr 《Planetary and Space Science》1977,25(10):985-988

High resolution spectra of the 6300 Å and 5200 Å regions of the night sky have been obtained using a 1 m spectrometer. Typical errors in measurements of $\text{O}\text{(}{}^1\text{D}\text{)}$ 6300 Å and $\text{N}\text{(}{}^2\text{D}\text{)}$ 5200 Å intensities due to contanimation by overlapping OH emissions have been calculated for a fixed-filter photometer, a tilting-filter photometer and a spectrophotometer. The importance of careful selection of certain instrumental parameters in order to minimize measurement errors is emphasized.  相似文献   

Auroral implications of recent measurements on O(1S) and O(1S) formation in the reaction of N+ with O2     

Andrew O. Langford  Veronica M. Bierbaum  Stephen R. Leone 《Planetary and Space Science》1985,33(10):1225-1228

Recent flowing afterglow measurements have shown that the reaction of N⁺ with O₂ produces 70 ± 30% of the oxygen atom product as $\text{O}\text{(}{}^1\text{D}\text{)}$ and < 0.1% as $\text{O}\text{(}{}^1\text{S}\text{)}$. These results indicate that this reaction does not contribute to the auroral green line emission (5577 Å), but can account for ～10% of the observed red line (6300 Å) auroral emission.  相似文献   

Non-thermal $\text{O}\text{(}{}^1\text{D}\text{)}$ produced by dissociative recombination of O₂⁺: A theoretical model and observational results     

G.A. Schmitt  V.J. Abreu  P.B. Hays 《Planetary and Space Science》1981,29(10):1095-1099

Thermal and non-thermal $\text{O}\text{(}{}^1\text{D}\text{)}$ number density profiles are calculated. The two populations are assumed to be coupled by a thermalization cross-section which determines the loss and production in the non-thermal and thermal populations, respectively. The sources, sinks and transport of the two populations are used to model volume emission rate profiles at 6300 Å. The 6300 Å brightness measured by the Visible Airglow Experiment is then used to establish the presence of the non-thermal population and to determine the thermalization cross-section.  相似文献   

A self-consistent evaluation of the rate constants for the production of the OI 6300 Å airglow     

R. Link  J.C. McConnell  G.G. Shepherd 《Planetary and Space Science》1981,29(6):589-594

The quenching rate k_N2 of $\text{O(}{}^1\text{D)}$ by N₂ and the specific recombination rate α_1D of O₂⁺ leading to $\text{O(}{}^1\text{D)}$ are re-examined in light of available laboratory and satellite data. Use of recent experimental values for the $\text{O(}{}^1\text{D)}$ transition probabilities in a re-analysis of AE-C satellite 6300 Å airglow data results in a value for k_N2 of 2.3 × 10^?11 cm³s^?1 at thermospheric temperatures, in excellent agreement with the laboratory measurements. This implies a value of J_O2 = 1.5 × 10^?6s^?1 for the O₂ photodissociation rate in the Schumann-Runge continuum. The specific recombination coefficient α_1D = 2.1 × 10^?7cm³s^?1 is also in agreement with the laboratory value. Implications for the suggested $\text{N}\text{(}{}^2\text{D) + O}{}_2\text{→ O(}{}^1\text{D) + NO}$ reaction are discussed.  相似文献   

Quenching of O⁺(²D) by electrons in the thermosphere     

Marsha R. Torr  D.G. Torr  P. Richards 《Planetary and Space Science》1980,28(6):581-584

A major loss process for the metastable species, O⁺(²D), in the thermosphere is quenching by electrons .To date no laboratory measurement exists for the rate coefficient of this reaction. Thermospheric models involving this process have thus depended on a theoretically calculated value for the rate coefficient and its variation with electron temperature. Earlier studies of the O⁺(²D) ion based on the Atmosphere Explorer data gathered near solar minimum, could not quantify this process. However, Atmosphere Explorer measurements made during 1978 exhibit electron densities that are significantly enhanced over those occurring in 1974, due to the large increases that have occurred in the solar extreme ultraviolet flux. Under such conditions, for altitudes ? 280 km, the electron quenching process becomes the major loss mechanism for O⁺(²D), and the chemistry of the N⁺₂ ion, from which the O⁺(²D) density is deduced, simplifies to well determined processes. We are thus able to use the in situ satellite measurements made during 1978 to derive the electron quenching rate coefficient. The results confirm the absolute magnitude of the theoretical calculation of the rate coefficient, given by the analytical expression k(T_e) = 7.8 × 10^?8 (T_e/300)^?0.5cm³s^?1. There is an indication of a stronger temperature dependence, but the agreement is within the error of measurement.  相似文献   

Further quantification of the sources and sinks of thermospheric O¹D) atoms     

D.G. Torr  P.G. Richards  M.R. Torr  V.J. Abreu 《Planetary and Space Science》1981,29(6):595-600

In this paper we confirm an earlier finding that the reaction constitutes a major source of OI 6300 Å dayglow. The rate coefficient for this reaction is found to be consistent with an auroral result, namely k₁ ≈ 6 × 10^?12cm³s^?1. We correct an error in an earlier publication and demonstrate that reaction (1) is consistent with the laboratory determined quenching rate for the reaction where $\text{k}{}_2\text{= 2.3 × 10}{}^{\mathrm{?11}}\text{cm}{}^3\text{s}{}^{\mathrm{?1}}$. Dissociative recombination of O⁺₂ with electrons is found to be a major daytime source in summer above ～220 km.  相似文献   

Charge exchange of metastable D oxygen ions with N₂ in the thermosphere     

D. G. Torr  N. Orsini 《Planetary and Space Science》1977,25(12):1171-1176

Measurements of N₂⁺ and supporting data made on the Atmosphere Explorer-C satellite in the ionosphere are used to study the charge exchange process The equality k = (5 ± 1.7) × 10^?10cm³s^?1. This value lies close to the lower limit of experimental uncertainty of the rate coefficient determined in the laboratory. We have also investigated atomic oxygen quenching of O⁺(²D) and find that the rate coefficient is 2 × 10^?11 cm³s^?1 to within approximately a factor of two.  相似文献   

A discussion of the energy transfer from N₂(A³Σ_u⁺) to $\text{O}\text{(}{}^1\text{S}$) in pulsating aurora     

Asgeir Brekke 《Planetary and Space Science》1973,21(4):698-702

In a recent paper, Brekke and Pettersen (1972) have introduced a method for estimating any indirect process in the production of the $\text{O}\text{(}{}^1\text{S}$) atoms in pulsating aurora; for 38 per cent of their data they found that the decay time for the indirect mechanism was shorter than the effective lifetime of the ${}^1\text{S}$ state. These data are related to the energy transfer from the N₂(A³Σ) molecules to the $\text{O}\text{(}{}^1\text{S)}$ state, and evidence is found for this process to contribute in the altitude range below 125 km.  相似文献   

An indirect mechanism for the production of O(¹S) in the aurora     

B.H. Solheim  E.J. Llewellyn 《Planetary and Space Science》1979,27(4):473-479

Recent laboratory measurements of the deactivation rate constants for O(¹S) have suggested that the dominant production mechanism for the green line in the nightglow is a two-step process. A similar mechanism involving energy transfer from an excited state of molecular oxygen is considered as a potential source of the OI (5577 Å) emission in the aurora. It is shown that the mechanism, $\text{O}{}_2\text{+ e → O}{}_2{}^1\text{+ e O}{}_2{}^1\text{+ O → O}{}_2\text{+ O(}{}^1\text{S}\text{)}$, is consistent with auroral observations; the intermediate excited state has been tentatively identified as the O₂(c¹∑^?_u) state. For the proposed energy transfer mechanism to be the primary source of the auroral green line, the peak electron impact cross-section for O₂¹ production must be approximately 2 × 10^?17 cm².  相似文献   

The O(1S) quantum yield from O2+ dissociative recombination     

D.R. Bates  E.C. Zipf 《Planetary and Space Science》1980,28(11):1081-1086

Recent laboratory studies show that the $\text{O}\text{(}{}^1\text{S}\text{)}$ quantum yield, $\text{f}\text{(}{}^1\text{S}\text{)}$, from O₂⁺ dissociative recombination varies considerably with the degree r of vibrational excitation. However, the suggestion that the high values for $\text{f}\text{(}{}^1\text{S}\text{)}$ deduced from airglow and auroral observations can be explained by invoking vibrational excitation, creates a number of problems. Firstly, the rapid vibrational deactivation of O₂⁺ ions by collisions with O atoms will keep r too low to account for the magnitude of $\text{f}\text{(}{}^1\text{S}\text{)}$; secondly, r varies considerably from one atmospheric source to another but its relative values (which should be reliable) do not co-vary with those of $\text{f}\text{(}{}^1\text{S}\text{)}$; thirdly, because r increases markedly above the peak of the $\text{X5577}\text{A}\text{?}$ dissociative recombination layer, the fits which theorists have obtained to the observed volume emission rate profiles would have to be regarded as fortuitious. It is tentatively suggested that $\text{f}\text{(}{}^1\text{S}\text{)}$ is higher in the airglow and aurora than in the laboratory plasma studied by Zipf (1980) because of the electron temperature dependence of the $\text{O}\text{(}{}^1\text{S}\text{)}$ specific recombination coefficient for O₂⁺(v^' ? 3) ions.The repulsive ${}^1\text{Σ}{}_{\mathrm{<mtext>u</mtext>}}\text{[}{}^1\text{D}\text{+}{}^1\text{s}\text{]}$ state of O₂ does not provide a suitable channel for the dissociative recombination. A possible alternative is the bound ${}^3\text{Π}{}_{\mathrm{<mtext>u</mtext>}}\text{[}{}^5\text{S}\text{+}{}^3\text{s}\text{]}$ state with predissociation to the repulsive ${}^3\text{Π}{}_{\mathrm{<mtext>u</mtext>}}\text{[}{}^3\text{P}\text{+}{}^1\text{s}\text{]}$ state.  相似文献   

The excitation of atomic oxygen to the $\text{O(}{}^1\text{S)}$ level by energy transfer from N₂(A³∑_u⁺) molecules in aurora     

Kjell Henriksen 《Planetary and Space Science》1973,21(5):863-871

The part that the energy transfer reaction $\text{N}{}_2\text{(A}{}^3\text{∑}{}_{\mathrm{u}}{}^{\mathrm{+}}\text{) + O(}{}^3\text{P) → N}{}_2\text{(X}{}^1\text{∑}{}_{\mathrm{g}}{}^{\mathrm{+}}\text{) + O(}{}^1\text{S)}$ plays in the excitation of the auroral green line has been investigated. The contribution is estimated to be 40 per cent in this case, containing pulsating aurora in class IBC 1. Due to greater quenching of the A³∑_u⁺ state, the centroid of the VK emission is displaced 10 km upwards of the green line height, which is centred at 110 km.  相似文献   

Branching ratios for the photoionization cross section of atomic oxygen     

A.K. Pradhan 《Planetary and Space Science》1980,28(2):165-167

Branching ratios $\text{σ(}\text{O}{}^0{}^3\text{P}\text{→}\text{O}{}^{\mathrm{+}}{}^2\text{D}{}^0\text{)}\text{σ(}\text{O}{}^0{}^3\text{P}\text{→}\text{O}{}^{\mathrm{+}}{}^4\text{S}{}^0\text{)}$ and $\text{σ(}\text{O}{}^0{}^3\text{P}\text{→}\text{O}{}^{\mathrm{+}}{}^2\text{P}{}^0\text{)}\text{σ (}\text{O}{}^0{}^3\text{P}\text{→}{}^4\text{S}{}^0\text{)}$ are calculated at 584 Å and 304 A employing the close-coupling approximation to compute the photoionization cross section values. The coupled channels include the states dominated by the ground configuration 1s²2s²p³ of O⁺and the next excited configuration ls²2s2p⁴. It is found that the partial c section $\text{σ(}{}^2\text{D}{}^0\text{)}$ decreases more rapidly than $\text{σ(}{}^2\text{P}{}^0\text{)}$, and at the lower wavelength 304 Å, the ratio $\text{σ(}{}^2\text{D}{}^0\text{)}\text{σ(}{}^4\text{S}{}^0\text{)}\text{<}\text{σ(}{}^2\text{P}{}^0\text{)}\text{σ(}{}^4\text{S}{}^0\text{)}$. Present results at 304 Å differ considerably from previous work.  相似文献   

Emission line shapes produced by dissociative excitation of atmospheric gases     

E.C. Zipf  W.C. Wells 《Planetary and Space Science》1980,28(8):859-866

Special line shapes are derived fro the λ 1356 Å (${}^5\text{S}{}^0\text{-}{}^3\text{P}$) transition of atomic oxygen from metastable (${}^5\text{S}{}^0\text{-}{}^3\text{P}$) time-of-flight spectra produced by electron impact dissociative excitation of O₂, CO₂, CO, and NO, and they are compared with the broadened λ 1304 A resonance line shapes deduced by Poland and Lawrence (1973) from atomic oxygen absorption studies. The non-thermal line shapes for both airglow emission features are shown to have an effective width comparable to a 60,000 K thermal doppler line shape for an electron impact energy of 100eV. The variation of the effective line width with electron-impact energy from threshold to 300 eV is given. Since the effective line width of the resonance radiation produced by dissociative excitation is very large compared with the doppler absorption widths of the ambient O atoms at normal exospheric temperatures, the anomalously broadened resonance lines will propagate through a planetary atmosphere as though they were optically thin. Thus, electron-impact dissociation of CO and CO₂ will contribute to the observed optically thin component of the λ 1304 Å emission in the upper atmospheres of Venus and Mars. However, the process cannot account for more than 10% of the observed optically thin emission because of the small magnitude of the excitation cross-section and the comparatively high-energy threshold for the process. The possibility that the source of the kinetically energetic $\text{O}\text{(}{}^3\text{S}$) atoms is the dissociative recombination of vibrationally excited CO₂⁺ ions is discussed.  相似文献   

On the simultaneous ionization-excitation of the OII(λ834 Å) resonance transition by electron impact on atomic oxygen     

E.C. Zipf  W.W. Kao  P.W. Erdman 《Planetary and Space Science》1985,33(11):1309-1312

Laboratory cross-section data on the excitation of the OII(2s 2p⁴⁴P → 2s² 2p³⁴S; λ834 Å) resonance transition and on the production of O⁺ and O²⁺ ions by electron impact on atomic oxygen are used to show that the ratio $\text{σ(λ834}\text{A}\text{?}\text{)}\text{σ(O}{}^{\mathrm{+}}\text{+ O}{}^{\mathrm{2+}}\text{)}$ is nearly constant for incident electron energies > 50 eV. Under auroral conditions, the total electron-ion pair production rate from electron impact on O can be inferred from λ834 Å volume emission rate measurements using the result that $\text{η(O}{}^{\mathrm{+}}\text{+ O}{}^{\mathrm{2+}}\text{)}\text{\$}\text{?}\text{8.4η(λ834}\text{A}\text{?}\text{)}$. These findings, along with earlier work on the simultaneous ionization-excitation of the 1 Neg (0,0) band of N₂⁺ and the 1 Neg (1, 0) band of O⁺₂, allow the specific ionization rates for the principal atmospheric constituents (O⁺, O⁺₂, N⁺₂), for the multiply-ionized species (O²⁺, O²⁺₂, N²⁺₂), and for the dissociatively produced atomic ions to be inferred in aurora from remote satellite observations.  相似文献   

The excitation of the 557.7 nm line and Herzberg bands in the nightglow     

L. Thomas  R.G.H. Greer  P.H.G. Dickinson 《Planetary and Space Science》1979,27(7):925-931

Measurements of the emission intensities of the 557.7 nm line and Herzberg bands and of O(³P) concentrations carried out on two coordinated rocket flights at South Uist during the night of 8/9 September 1975 are presented. An examination of the 557.7 nm emission and $\text{O}\text{(}{}^3\text{P}\text{)}$ data on the basis of recent data on relevant rate coefficients has shown that the results can be interpreted on the basis of the Barth mechanism for the production of $\text{O}\text{(}{}^1\text{S}\text{)}$ atoms but not the Chapman mechanism. Evidence is provided that the A³Σ⁺_u state of O₂ could be responsible for the $\text{O}\text{(}{}^1\text{S}\text{)}$ production in the Barth mechanism. Values of the rate coefficients involved are deduced from a comparison of the 557.7 nm and Herzberg emission rates.  相似文献   

A dynamical effect in the ionospheric f₁ layer     

C. Taieb  G. Scialom  G. Kockarts 《Planetary and Space Science》1978,26(11):1007-1016

Incoherent scatter observations of the ionospheric F₁ layer above Saint-Santin (44.6°N) are analyzed after correction of a systematic error at 165 and 180 km altitude. The daytime valley observed around 200 km during summer for low solar activity conditions is explained in terms of a downward ionization drift which reaches ?30 m s^?1 around 180 km. Experimental determinations of the ion drift confirm the theoretical characteristics required for the summer daytime valley as well as for the winter behaviour without a valley. The computations require an effective dissociative recombination rate of $\text{2.3 × 10}{}^{\mathrm{?7}}\text{(}\text{300/}\text{T}{}_{\mathrm{e}}\text{)}{}^{0.7}\text{(}\text{cm}{}^3\text{s}{}^{\mathrm{?1}}\text{)}$ and ionizing fluxes compatible with solar activity conditions at the time when the valley is observed.  相似文献   

Cross-section for the dissociative photoionization of hydrogen by 584 Å radiation: The formation of protons in the Jovian ionosphere     

K.M. Monahan  W.T. Huntress  A.L. Lane  J.M. Ajello  T.E. Burke  P. Le Breton  A. Williamson 《Planetary and Space Science》1974,22(1):143-149

The cross-section for dissociative photoionization of hydrogen by 584 Å radiation has been measured, yielding a value of 5 × 10^?20 cm². The process can be explained as a transition from the $\text{X}{}^1\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{+}}$ ground state to a continuum level of the $\text{X}{}^2\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{+}}$ ionized state of H₂ The branching ratio for proton (H⁺) vs molecular ion (H₂⁺) production at this energy is 8 × 10^?3. This process is quite likely an important source of protons in the Jovian ionosphere near altitudes where peak ionization rates are found.  相似文献   

Upper atmospheric temperatures from Doppler line widths—V. Auroral electron energy spectra and fluxes deduced from the 5577 and 6300 Å atomic oxygen emissions     

H.H. Zwick  G.G. Shepherd 《Planetary and Space Science》1973,21(4):605-621

This is a report upon further data obtained from the auroral OI 5577 Å emission with a Wide Angle Michelson Interferometer (WAMI), and upon our first observations made with it on the 6300 Å emission. The method used for converting emission intensities and temperatures to auroral electron fluxes and energy spectra is described. Data for the 5577 Å emission are presented for the (lack of) heating in auroral forms, vertical temperature profiles in aurora, electron flux and energy spectrum variations in pulsating aurora, and a ‘cold’ subvisual auroral arc. Data from the OI 6300 Å emission are presented for the diurnal variation of exospheric temperature and for the thermalization of $\text{O}\text{(}{}^1\text{D)}$ in the F-region.  相似文献   

The green light of the night sky     

D.R. Bates 《Planetary and Space Science》1981,29(10):1061-1067

The development of the theory of the 5577 Å emission from the upper atmosphere is reviewed. Evidence from both aeronomy and chemical kinetics shows that the Barth mechanism is a much more important source of $\text{O}\text{(}{}^1\text{S}\text{)}$ than in the Chapman process. The molecular oxygen state involved is probably c¹Σ^?_u (the upper state of the Herzberg II band system).  相似文献   

Associative ionization of N(²D) and O     

M.R. Torr  D.G. Torr 《Planetary and Space Science》1979,27(10):1233-1237

Recent laboratory measurements have shown that N(²P) atoms, and thus probably hot N(²D) atoms, will recombine with atomic oxygen via an associative ionization process at the gas kinetic rate. While the reaction is endothermic, it has been suggested that this has interesting implications for the upper atmosphere in that N(²D) atoms in the tail of the velocity distribution could provide an additional source of NO⁺ through the reverse of the dissociative recombination reaction . It has also been suggested that this process might account for the difference between a laboratory determination of the rate coefficient and that determined from the Atmospheric Explorer Satellite data. In this paper we investigate further the likelihood of the associative ionization of N(²D) and O playing a significant role in the normal ionosphere, in the light of several recent relevant studies. We conclude that the associative ionization process is not an important factor and that a more probable cause for disagreements in the various determinations of the recombination coefficient, is the difference in excited states of the ions in the various experiments.  相似文献