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   

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   

Linewidth studies on the NI(⁴S−⁴P) resonance multiplet     

P.W. Erdman  E.C. Zipf 《Planetary and Space Science》1983,31(11):1291-1298

We have measured the linewidths of the NI multiplets $\text{[2p}{}^2\text{3p}{}^4\text{D}{}^0\text{?2p}{}^2\text{3s}{}^4\text{P, λ8691}\text{A}\text{?}\text{; 2p}{}^2\text{3p}{}^4\text{P}{}^0\text{?2p}{}^2\text{3s}{}^4\text{P, λ8212}\text{A}\text{?}\text{; 2p}{}^2\text{3s}{}^4\text{P?2p}{}^3{}^4\text{S}{}^0\text{, λ1200}\text{A}\text{?}\text{]}$ produced in the dissociative excitation of N₂ by energy electrons. The infrared transitions excite the N(⁴P) resonance state by cascade and they account for > 50% of the total N(⁴P) cross section at 100 eV. Both the i.r. and v.u.v. lines are found to be highly Doppler broadened ( ～ 25 times the thermal Doppler line width). These results indicate that dissociative excitation of N₂ produces N (⁴P) atoms with sufficient kinetic energy so that the $\text{λ1200}\text{A}\text{?}$ resonance radiation $\text{[2p}{}^2\text{3s}{}^4\text{P ?2p}{}^3{}^4\text{S}{}^0\text{]}$ emitted by these excited atoms would be optically thin in the Earth's upper atmosphere. We also found that the line strength ratios for the resolved components of the $\text{λ1200}\text{A}\text{?}$ triplet excited by dissociative excitation differ from those predicted by the multiplicities of the states involved and used in current entrapment models; the intensity ratios also vary with the energy of the incident electron. These developments introduce new complications into the analysis of the terrestrial ultraviolet dayglow.  相似文献   

Geopotential coefficients of order 29, from analysis of the orbit of satellite 1967-104B     

Doreen M.C. Walker 《Planetary and Space Science》1984,32(6):717-725

The orbit of the satellite 1967-104B has been analysed as it passed through 29:2 resonance with the Earth's gravitational field between January 1977 and September 1978. From the changes in inclination and eccentricity the following lumped 29th-order geopotential harmonic coefficients were obtained: $\text{10}{}^9\text{C}\text{?}{}_{29}{}^{0.2}\text{= 4.1 ± 0.8}$, $\text{10}{}^9\text{S}\text{?}{}_{29}{}^{0.2}\text{= 10.3 ± 2.4}$, $\text{10}{}^9\text{C}\text{?}{}_{29}{}^{1.1}\text{= ? 160 ± 19}$, $\text{10}{}^9\text{S}\text{?}{}_{29}{}^{1.1}\text{= 79 ± 10}$, $\text{10}{}^9\text{C}\text{?}{}_{29}{}^{\mathrm{?1.3}}\text{= 38 ± 14}$, $\text{10}{}^9\text{S}\text{?}{}_{29}{}^{\mathrm{?1.3}}\text{= 19 ± 5}$. These values have been compared with existing comprehensive geopotential models: the best agreement is with the model of Rapp (1981).  相似文献   

The possible effects of translationally excited nitrogen atoms on lower thermospheric odd nitrogen     

Susan Solomon 《Planetary and Space Science》1983,31(1):135-139

In the quiet lower thermosphere, photolysis of N₂ produces translationally excited $\text{N}\text{(}{}^4\text{S}\text{)}$ and $\text{N}\text{(}{}^2\text{D}\text{)}$ atoms. A fraction of these $\text{N}\text{(}{}^4\text{S}\text{)}$ atoms may react rapidly with O₂ while still translationally hot. This results in substantially larger calculated NO densities than those obtained if translational excitation is not considered. The sensitivity of the calculated NO density in the lower thermosphere to this process is examined.  相似文献   

Changes in the concentration of mesospheric ozone during the total solar eclipse     

V.V. Agashe  S.M. Rathi 《Planetary and Space Science》1982,30(5):507-513

Measurements of dayglow radiance of $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{g}}\text{)}$ and OH(7,2) bands are reported. Ground based photometers were used to monitor zenith radiance of 1270 and 694 nm emissions during the total solar eclipse of 16 February 1980. Altitude distribution of 1270 nm intensity was derived from ground based observations. A set of altitude distributions of $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{g}}\text{)}$ were thus obtained throughout the eclipse. These altitude distributions were converted into ozone distributions using the rate equations for formation and loss of ozone and $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{g}}\text{)}$ molecules. Results indicate an increase in the ozone concentration at mid-eclipse. OH(7,2) emission did not show enhancement during totality. This may mean that there was no increase in OH concentration during the eclipse.  相似文献   

Relationship between the growth of the ring current and the interplanetary quantity ε     

S.-I. Akasofu 《Planetary and Space Science》1979,27(7):1039-1041

When the interplanetary parameter $\text{ε(= VB}{}^2\text{sin}{}^4\text{(}\text{θ}\text{2}\text{)l}{}_0{}^2\text{)}$ exceeds the amount that can be dissipated by the ionosphere in terms of the Joule heat production, the excess energy is absorbed by the ring current belt, resulting in abnormal growth of the Dst index.  相似文献   

Quantal calculation of the lifetime of N+(5S) and the λ2145Å auroral mystery feature     

A. Hibbert  D.R. Bates 《Planetary and Space Science》1981,29(2):263-268

The calculated radiative lifetime of the metastable ion is 6.4 × 10^?3s. Used in conjunction with the results of measurements by Erdman, Espy and Zipf this sets 1.3 × 10^?18 cm² as the upper limit to the cross section for the formation of $\text{N}{}^{\mathrm{+}}\text{(}{}^5\text{S}\text{)}$ in e - N₂ collisions at 100eV which leaves the possibility that the process is responsible for the $\text{λ2145}\text{A}\text{?}$ feature in auroras only just open. The cross section for the formation of $\text{N}{}^{\mathrm{+}}\text{(}{}^5\text{S}\text{)}$ in e — N collisions is large. However for this process to lead to the observed intensity of $\text{λ2145}\text{A}\text{?}$ relative to $\text{λ3914}\text{A}\text{?}$ the N:N₂ abundance ratio would have to be as high as 1.6 × 10^?2.  相似文献   

The locating of hydromagnetic whistler sources and determination of their generating proton spectra     

Ja.L. Al&#x;pert  D.S. Fligel 《Planetary and Space Science》1977,25(5):487-497

Results are given of the calculations of the group delay time propagating τ(ω, φ₀) of hydromagnetic whistlers, using outer ionospheric models closely resembling actual conditions. The τ(ω, φ₀) dependencies were compared with the experimental data of τ_exp(ω, φ₀) obtained from sonagrams. The sonagrams were recorded in the frequency range $\text{? ? (0.5?2.5) Hz}$ at observation points located at geomagnetic latitudes φ₀ = (53?66)° and in the vicinity of the geomagnetic poles. This investigation has led us to new and important conclusions.The wave packets (W.P.) forming hydromagnetic whistlers (H.W.) are mainly generated in the plasma regions at L = 3.5?4.0. This is not consistent with ideas already expressed in the literature that their generation region is $\text{L ? 3?10}$. The overwhelming majority of the τ_exp values differ considerably from the times at which wave packets would, in theory, propagate along the magnetic field lines corresponding to those of the geomagnetic latitudes φ₀ of the observation points. The second important fact is that the W.P. frequency ω is less than $\text{Ω}{}_{\mathrm{H}}$ everywhere along its propagation trajectory, including the apogee of the magnetic force line ($\text{Ω}{}_{\mathrm{H}}$ is the proton gyrofrequency). Proton flux spectra $\text{E ? (30?120)}$ keV, responsible for H.W. generation, were determined. Comparison of the Explorer-45 and OGO-3 measurements published in the literature, with our data, showed that the proton flux density energy responsible for the H.W. excitation $\text{N}{}_{\mathrm{p}}\text{(}\text{MV}{}_6{}^2\text{2}\text{) ? (5 × 10}{}^{\mathrm{?3}}\text{?10}{}^{\mathrm{?1}}\text{)}\text{H}{}_{\mathrm{a}}{}^2\text{8π}$ where H_a is the magnetic field force in the generation region of these W.P. The electron concentration is $\text{N}{}_{\mathrm{a}}\text{? (10}{}^2\text{?10}{}^3\text{) cm}{}^{\mathrm{?3}}$. The values given in the literature are $\text{N}{}_{\mathrm{a}}\text{? (10}{}^{\mathrm{?10}}\text{?10}{}^3\text{) cm}{}^{\mathrm{?3}}$. The e data considered also leads to the conclusion that the generating mechanism of the W.P. studied probably always co-exists with the mechanism of their amplification.  相似文献   

Effects of crossed magnetic and (spatially dependent) electric fields on charged particle motion     

K.D. Cole 《Planetary and Space Science》1976,24(5):515-518

The motion of charged particles is examined in the case of a homogeneous magnetic field B together with an orthogonal electric field E, which has a gradient ▽E parallel to E. If , the particles drift at right angles to E and B with a modified gyrofrequency and produce a current in that direction. If , the particles not only drift in the direction of E × B but are also accelerated in the direction of E, in which direction they also produce a current.  相似文献   

Love numbers of the giant planets     

S.V. Gavrilov  V.N. Zharkov 《Icarus》1977,32(4):443-449

We calculate the Love numbers k_n for n = 2 to 10, and determine the “gravitational noise” from tides. The new values k₂ for Jupiter, Saturn, and Uranus yield new estimates for the planetary dissipation functions: $\text{Q}{}_{\mathrm{<mtext>J</mtext>}}\text{? 2.5 × 10}{}^4$, $\text{Q}{}_{\mathrm{<mtext>S</mtext>}}\text{? 1.4 × 10}{}^4\text{, Q}{}_{\mathrm{<mtext>U</mtext>}}\text{? 5 × 10}{}^3$.  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   

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   

Distribution functions for energetic oxygen atoms in the earth's lower atmosphere     

Jennifer A. Logan  Michael B. McElroy 《Planetary and Space Science》1977,25(2):117-122

Direct photolysis of O₃ and quenching of $\text{O}\text{(}{}^1\text{D}\text{)}$ by N₂ provide abundant sources of fast oxygen atoms for the Earth's lower atmosphere. The concentration of atoms with energy above 0.7 eV may exceed the concentration of $\text{O}\text{(}{}^1\text{D}\text{)}$ for all altitudes below 18 km and these atoms may play an important role in lower atmospheric chemistry. Distribution functions for $\text{O}\text{(}{}^3\text{P}\text{)}$ are given for the energy interval 0.1-1.3 eV, for a range of altitudes from 0 to 62 km.  相似文献   

Thermal inertia mapping of Mars from 60°S to 60°N     

Frank Don Palluconi  Hugh H. Kieffer 《Icarus》1981,45(2):415-426

Twenty-micrometer brightness temperatures are used to derive the thermal inertia for 81% of the Martian surface between latitudes ±60°. These data were acquired by the two Viking Infrared Thermal Mappers in 1977 and 1978 following the two global dust storms of 1977. The spatial resolution used is 2° in latitude by 2° in longitude and the total range in derived inertia is $\text{1}\text{to}\text{15 × 10}{}^{\mathrm{?3}}\text{cal cm}{}^{\mathrm{?2}}\text{sec}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}\text{°}\text{K}{}^{\mathrm{?1}}$. The distribution of thermal inertia is strongly bimodal with all values of thermal inertia less than $\text{4 × 10}{}^{\mathrm{?3}}\text{cal cm}{}^{\mathrm{?2}}\text{sec}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}\text{°}\text{K}{}^{\mathrm{?1}}$ being associated with three disjoint bright regions mostly in the northern hemisphere. Sufficient dust is raised in global storms to provide fine material adequate to produce these low-inertia areas but the specific deposition mechanism has not been defined. At the low resolution used, no complete exposures of clean rock were found. There is some tendency for darker material to be associated with higher thermal inertia, although the trend is far from one to one. The distribution of high- and low-inertia areas is sufficiently nonrandom to produce a variation in whole-disk brightness temperature with central meridian longitude. This variation and the change in surface kinetic temperature associated with dust storms are factors in establishing the whole-disk brightness temperature at radio and infrared wavelengths and will be important for those who use Mars as a calibration source.  相似文献   

Photoionization of barium clouds via the ${}^3\text{D}$ metastable levels     

J.L. Carlsten 《Planetary and Space Science》1975,23(1):53-60

The photoionization of optically thin barium clouds is analyzed and shown to occur primarily by a two-step process involving the ${}^3\text{D}$ metastable term as the ntermediate state. The equilibrium populations of the ${}^1\text{D}$ and ${}^3\text{D}$ metastable levels are calculated and found to differ significantly from the values now in the literature. These populations are combined with our newly available photoionization data to calculate the resulting photoionization rate in the upper atmosphere.  相似文献   

The determination and analysis of the orbit of NIMBUS 1 ROCKET, 1964-52B: Part 2: Variations in orbital eccentricity     

W.J. Boulton 《Planetary and Space Science》1985,33(6):735-756

The influence of aerodynamic drag and the geopotential on the motion of the satellite 1964-52B is considered. A model of the atmosphere is adopted that allows for oblateness, and in which the density behaviour approximates to the observed diurnal variation. A differential equation governing the variation of the eccentricity, e, combining the effects of air drag with those of the Earth's gravitational field is given. This is solved numerically using as initial conditions 310 computed orbits of 1964-52B.The observed values of eccentricity are modified by the removal of perturbations due to luni-solar attraction, solid Earth and ocean tides, solar radiation pressure and low-order long-periodic tesseral harmonic perturbations. The method of removal of these effects is given in some detail. The behaviour of the orbital eccentricity predicted by the numerical solution is compared with the modified observed eccentricity to obtain values of atmospheric parameters at heights between 310 and 430 km. The daytime maximum of air density is found to be at 14.5 hours local time. Analysis of the eccentricity near 15th order resonance with the geopotential yielded values of four lumped geopotential harmonics of order 15, namely: $\text{10}{}^9\text{C}{}^{\mathrm{1,0}}{}_{15}\text{= ?78.8 ± 7.0}$, $\text{10}{}^9\text{S}{}^{\mathrm{1,0}}{}_{15}\text{= ?69.4 ± 5.3}$, $\text{10}{}^9\text{C}{}^{\mathrm{?1,2}}{}_{15}\text{= ?41.6 ± 3.5}$$\text{10}{}^9\text{S}{}^{\mathrm{?1,2}}{}_{15}\text{= ?26.1 ± 8.9}$, at inclination 98.68°.  相似文献   

The chemistry of metastable species in the Venusian ionosphere     

J.L. Fox 《Icarus》1982,51(2):248-260

Reactions of metastable species are important in determining the densities of minor ions in the Venusian ionosphere. Calculations are carried out in which the coupled continuity and momentum equations are solved for twelve ions and four neutral species in the dayside ionosphere, including $\text{O}{}^{\mathrm{+}}\text{(}{}^2\text{D),}\text{O}{}^{\mathrm{+}}\text{(}{}^2\text{P),}\text{N}\text{(}{}^2\text{D),}\text{and N}\text{(}{}^2\text{P)}$. Altitude profiles of these metastable species are presented. Their reactions are shown to be a significant source of several minor ions, especially N₂⁺, CO⁺, and N⁺. The discrepancies which existed between model and measured densities of these ions are resolved.  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   

Small-scale turbulence in the atmosphere of Venus     

Richard Woo  J.W. Armstrong  A.J. Kliore 《Icarus》1982,52(2):335-345

Previous studies based on radio scintillation measurements of the atmosphere of Venus have identified two regions of small-scale temperature fluctuations located in the vicinity of 45 and 60 km. A global study of the fluctuations near 60 km, which are consistent with wind-shear-generated turbulence, was conducted using the Pioneer Venus measurements. The structure constants of refractive index fluctuations c_n² and temperature fluctuations c_T² increase poleward, peak near 70° latitude, and decrease over the pole; c_n² varies from 2 × 10^?15 to 1.5 × 10^?14m^{$\text{2}\text{3}$} and c_T² from 4 × 10^?3 to 7 × 10^?2°K²m^{$\text{?2}\text{3}$}. These results indicate greater turbulent activity at the higher latitudes. In the region near 45 km the refractive index fluctuations and the corresponding temperature fluctuations are substantially lower. Based on the analysis of one representative occultation measurement, $\text{c}{}_{\mathrm{<mtext>n</mtext>}}{}^2\text{= 2 × 10}{}^{\mathrm{?16}}\text{m}{}^{\mathrm{<mtext>?2</mtext><mtext>3</mtext>}}\text{and}\text{c}{}_{\mathrm{<mtext>T</mtext>}}{}^2\text{= 7.3 × 10}{}^{\mathrm{?4}}\text{°}\text{K}{}^2\text{m}{}^{\mathrm{<mtext>?2</mtext><mtext>3</mtext>}}$ in the 45-km region. The fluctuations in this region also appear to be consistent with wind-shear-generated turbulence. The turbulence level is considerably weaker than that at 60 km; the energy dissipation rate ε is 4.9 × 10^?5m²sec^?3 and the small-scale eddy diffusion coefficient K is 2 × 10³ cm² sec^?1.  相似文献