Quenching Rates for Metastable Oxygen Atoms(5S0)

1973 ◽  
Vol 28 (5) ◽  
pp. 725-729 ◽  
Author(s):  
E.-P. Roth ◽  
D. Perner ◽  
J. W. Dreyer
Keyword(s):  
Oxygen Atom ◽  
Cross Section ◽  
Absorption Spectroscopy ◽  
Cross Sections ◽  
Rate Constants ◽  
Noble Gases ◽  
Rare Gas ◽  
Quenching Rate ◽  
Collision Efficiency ◽  
Molecular Gases

Metastable O (3s 5S0) atoms were produced by rare gas sensitized decomposition of various oxygen containing compounds. The quenching rate constants of H2 , N2, O2 , NO, N2O, N2O4/NO2, CO, CO2, SO2 , SO3 , H2O and the noble gases for the 0 (5S) have been measured by absorption spectroscopy. The noble gases, except xenon, deactivate the metastable oxygen atom with low collision efficiency. Xenon and molecular gases, except hydrogen, deactivate this species efficiently, the cross section being of the order of gas kinetic cross sections.

Calculation of Line Broadening Cross Sections for Level Crossing Experiments in Alkali-Rare Gas Systems

1974 ◽  
Vol 29 (4) ◽  
pp. 605-609
Author(s):  
B. Grosswendt
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Rare Gas ◽  
Atomic Interaction ◽  
Cross Section Data ◽  
Line Broadening ◽  
Crossing Experiments ◽  
Level Crossing ◽  
Section Data ◽  
Frame Work

Using a simple approximation for the theoretical atomic interaction constants cross section data for level crossing and Hanle-effect line broadening experiments in Rb, Mg+ and Ca+ rare gas systems could be derived. It is shown that in the Rb system the interaction C6R-6 is predominant and that the results are little influenced by dipole-quadrupole and repulsive interactions in the frame work of the Lindholm-Foley-Hindmarsh theory.

scholarly journals Liquid water absorption and scattering effects in DOAS retrievals over oceans

2014 ◽  
Vol 7 (12) ◽  
pp. 4203-4221 ◽  
Author(s):  
E. Peters ◽  
F. Wittrock ◽  
A. Richter ◽  
L. M. A. Alvarado ◽  
V. V. Rozanov ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Water Absorption ◽  
Cross Section ◽  
Absorption Spectroscopy ◽  
Cross Sections ◽  
Liquid Water ◽  
Natural Waters ◽  
Differential Optical Absorption Spectroscopy ◽  
Optical Absorption Spectroscopy ◽  
Offset Correction

Abstract. Spectral effects of liquid water are present in absorption (differential optical absorption spectroscopy – DOAS) measurements above the ocean and, if insufficiently removed, may interfere with trace gas absorptions, leading to wrong results. Currently available literature cross sections of liquid water absorption are provided in coarser resolution than DOAS applications require, and vibrational Raman scattering (VRS) is mostly not considered, or is compensated for using simulated pseudo cross sections from radiative transfer modeling. During the ship-based TransBrom campaign across the western Pacific in October 2009, MAX-DOAS (Multi-AXis differential optical absorption spectroscopy) measurements of light penetrating very clear natural waters were performed, achieving average underwater light paths of up to 50 m. From these measurements, the retrieval of a correction spectrum (H2Ocorr) is presented, compensating simultaneously for insufficiencies in the liquid water absorption cross section and broad-banded VRS structures. Small-banded structures caused by VRS were found to be very efficiently compensated for by the intensity offset correction included in the DOAS fit. No interference between the H2Ocorr spectrum and phytoplankton absorption was found. In the MAX-DOAS tropospheric NO2 retrieval, this method was able to compensate entirely for all liquid water effects that decrease the fit quality, and performed better than using a liquid water cross section in combination with a simulated VRS spectrum. The decrease in the residual root mean square (rms) of the DOAS fit depends on the measurement's contamination with liquid water structures, and ranges from ≈ 30% for measurements slightly towards the water surface to several percent in small angles above the horizon. Furthermore, the H2Ocorr spectrum was found to prevent misfits of NO2 slant columns, especially for very low NO2 scenarios, and thus increases the reliability of the fit. In test fits on OMI satellite data, the H2Ocorr spectrum was found selectively above ocean surfaces, where it decreases the rms by up to ≈ 11%.

Cross Section Ratios for the Electron Impact Production of Singly and Multiply Ionized Rare Gas Ions

1978 ◽  
Vol 33 (9) ◽  
pp. 1111-1113 ◽  
Author(s):  
F. Egger ◽  
T. D. Mark
Keyword(s):  
Electron Impact ◽  
Cross Section ◽  
Mass Spectrometer ◽  
Cross Sections ◽  
Impact Ionization ◽  
Rare Gas ◽  
Ionization Cross ◽  
Single Ionization ◽  
Multiple Ionization ◽  
Ionization Cross Sections

Electron impact ionization of He, Ne, Ar, Kr and Xe has been studied with a double focussing mass spectrometer Varian MAT CH5. Ratios of various multiple ionization cross sections with respect to single ionization cross sections for He, Ne, Ar, Kr and Xe at electron energies of 50, 100 and 150eV are given. These cross section ratios are com­pared with previous determinations.

Electron loss cross sections from rare gas atoms to Ar+

1982 ◽  
Vol 60 (7) ◽  
pp. 977-980
Author(s):  
B. Hird ◽  
S. P. Ali
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Energy Region ◽  
Rare Gas ◽  
Electron Loss ◽  
Rare Gases ◽  
Thin Target ◽  
Rare Gas Atoms ◽  
Good Agreement

Measurements of the σ10 cross section for a beam of Ar+ ions of energies between 30 and 120 keV passing through a thin target of the rare gases show good agreement with the few previous measurements in this energy region.

Positive ion production in single collisions of Cl− with rare gas atoms

1984 ◽  
Vol 62 (6) ◽  
pp. 544-547 ◽  
Author(s):  
B. Hird ◽  
F. Rahman
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Rare Gas ◽  
Electron Detachment ◽  
Centre Of Mass ◽  
Target Mass ◽  
Double Electron ◽  
Ion Production ◽  
Rare Gas Atoms ◽  
Positive Ion

The cross section σ−+ for double electron detachment from Cl− in a single collision with a rare gas atom has been measured between 12.5 and 122.5 keV. The magnitude of these cross sections shows that there is a good probability that a second electron will be emitted in collisions that detach one electron, particularly with light targets. The centre-of-mass cross section decreases with increasing target mass, but the variation is less than that for F− and O− double electron detachment cross sections.

Positron lifetime spectra for gases

1982 ◽  
Vol 60 (4) ◽  
pp. 503-516 ◽  
Author(s):  
G. R. Heyland ◽  
M. Charlton ◽  
T. C. Griffith ◽  
G. L. Wright
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Inert Gases ◽  
Gas Density ◽  
Molecular Gases ◽  
Free Positron ◽  
To Receive ◽  
Helium Neon ◽  
Limiting Value ◽  
Good Agreement

Recent observations on the lifetime spectra for gases are presented and discussed. There is little to report on the inert gases helium, neon, and argon and the spectra for these gases are thought to be understood. New lifetime data for krypton and xenon have revealed two fast components which, although probably connected with the low positronium fractions for these gases, have yet to receive a satisfactory interpretation.The polarized orbital calculations for Zeff's and momentum transfer cross sections for all the inert gases by the York group are now complete and are generally in good agreement with experiment.For the molecular gases some information on rotational excitation cross sections has been obtained from thermalization times for nitrogen, hydrogen, and deuterium. In general, the [Formula: see text] parameter is dependant on gas density and temperature with some gases showing a pronounced maximum in the density dependance. The gases C3H8, C4H10, and CH3Cl have very large values of [Formula: see text] which indicate localization or capture of the positron by one or more molecules. These three gases exhibit a maximum in the instantaneous decay rate of the "free" positron component at low densities from which a "capture" cross section can be estimated.The positronium fraction, F, generally increases with the gas density, usually approaching a limiting value asymptotically, but for nitrogen this density dependance has a maximum at ~ 140 amagat. No satisfactory explanation has been offered for this behaviour.Positronium formation cross sections for several gases have been deduced from measurements of the variation of F with the concentration of the gas in helium. These cross sections are similar in magnitude to those deduced from the total cross section beam measurements.

Luminescence of Diatomic Molecules II. Energy Dependence of Collisional Deactivation Cross Sections

1972 ◽  
Vol 27 (5) ◽  
pp. 769-776 ◽  
Author(s):  
F. J. Comes ◽  
F Speier
Keyword(s):  
Excited States ◽  
Cross Section ◽  
Cross Sections ◽  
Charged Particles ◽  
Molecular Ions ◽  
Thermal Velocity ◽  
Vibrational States ◽  
Molecular Gases ◽  
Exponential Law ◽  
The Cross

Abstract Photoionization has been used to produce ions of N2, O2. and CO in definite excited states. Deactivating collisions of these ions with molecular gases were described in paper I, where the cross sections of ions with thermal velocity are given for various electronic and vibrational states. By application of an electric field the charged particles are accelerated yielding information on the influence of the kinetic energy of the collision partners on these deactivating collisions. The cross section is found to follow an exponential law σ ~ E-α, with a varying between 0.34 and 0 41 for the different excited stales of the molecular ions. The observations were carried out for a range of kinetic energies from the thermal energy up to 6 eV maximum. This simple exponential law is followed for kinetic energies up to at least 2 eV. At higher energies slight deviations were found to occur

The determination of cross sections for quenching of resonance radiation of metal atoms III. Results for thallium

1968 ◽  
Vol 303 (1475) ◽  
pp. 467-475 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Cross Section ◽  
Cross Sections ◽  
Rate Constants ◽  
Resonance Radiation ◽  
Metal Atoms ◽  
The Cross

The intensity of fluorescence of thallium has been measured in hydrogen-oxygen flames diluted with each of the gases, argon, helium, nitrogen and carbon dioxide and the measurements used to obtain the following values for the quenching cross section (Å 2 ) for the 7 s 2 S ½ state of thallium σ 2 H 2 = 0.03, σ 2 O 2 = 13.2 ± 1.5, σ 2 N 2 = 6.4 ± 0.2, σ 2 H 2 O = 1.75 ± 0.2, σ 2 CO = 13.6 ± 0.8, σ 2 CO 2 = 32.5 ± 1.5, σ 2 Ar ≤ 0.1, σ 2 He ≤ 0.12. These values for the cross sections have been used to re-calculate the rate constants of the reactions, Tl + H + X → H X + Tl*, where X = H, OH, Cl or Br, from the data obtained by Phillips & Sugden (1961). The re-calculated values are lower than the original ones by a factor of 2.2.

Electron Excitation in Noble Gases

1975 ◽  
Vol 53 (7) ◽  
pp. 689-699 ◽  
Author(s):  
H. G. P. Lins De Barros ◽  
H. S. Brandi
Keyword(s):  
Differential Cross Section ◽  
Electron Impact ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Noble Gases ◽  
Electron Excitation ◽  
Wave Functions ◽  
Total Cross Sections ◽  
Collision Processes

Calculations for cross sections for some states of Ne excited by electron impact have been carried out. A parametrization of total and differential cross section in the Born–Ochkur approximation has been proposed. Using this parametrization and appropriate wave functions for the states involved in the collision processes, differential and total cross sections have been calculated. The results have shown that this parametrization is very convenient to study this type of problem.

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