Absolute photoionization cross sections of atomic oxygen



Publisher: National Aeronautics and Space Administration in [Washington, D.C.?

Written in English
Published: Downloads: 962
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Subjects:

  • Photoionization of gases,
  • Oxygen

Edition Notes

StatementJames A.R. Samson and P.N. Pareek
SeriesNASA-CR -- 173873, NASA contractor report -- 173873
ContributionsPareek, P. N, United States. National Aeronautics and Space Administration
The Physical Object
FormatMicroform
Pagination1 v.
ID Numbers
Open LibraryOL14928910M

Absolute differential and integral direct electron excitation cross sections have been measured for the three most intense autoionizing ³P → ³P° transitions in atomic oxygen (, , and Å) a Cited by: 6. REcent laboratory measurements of photoionization cross section s and ion state branching ratios for atomic oxygen, molecular nitrogen and molecular oxygen are combined with theoretical cross sections for soft x-ray absorption and tabulated for use in atmospheric photoionization calculations. The most important changes from earlier compilations for aeronomical calculations is a factor of Cited by: Absolute photoionization cross sections for Kr{sup 5+} were measured in the photon energy range eV using synchrotron radiation. For comparison, a detailed energy scan of the electron-impact ionization cross section was made in the same energy range and normalized to previously published absolute measurements. Absolute differential excitation cross sections of atomic oxygen (³P‐¹D transition) by electron impact have been measured by a crossed‐beam method. Atomic oxygen was generated by a thermal dissociation method. The energy and angular range covered were from 7 Cited by:

Cross section in photoemission. The photoemission is a useful experimental method for the determination and the study of the electronic states. Sometimes the small amount of deposited material over a surface has a weak contribution to the photoemission spectra, which makes its identification very knowledge of the cross section of a material can help to detect thin layers or 1D. Cross section. Not every interaction between a photon and an atom, or molecule, will result in photoionization. The probability of photoionization is related to the photoionization cross-section of the species, which depends on the energy of the photon (proportional to its wavenumber) and the species being considered. In the case of molecules, the photoionization cross-section can be estimated. Absorption cross sections and cross sections fot the production of atomic fluorescence by photodissociation in the region - Angstrom , The absolute cross section for photoionization of O 2 (1 G.N., Photo-absorption cross sections of molecular oxygen between Å and Absolute photoionization cross sections of atomic oxygen [microform] / James A.R. Samson and P.N. Pareek Dissociative and double photoionization cross sections of NO fromthreshold to A [microform] / James.

Two-Photon Absorption Cross Sections for Some Atoms and Molecules in the Ground State Table C.1 lists absorption cross sections for two-photon transitions in a number of atoms and simple molecules [1, 2], obtained experimentally and theoretically. For notation and dimensions, see Section The. The photoionization cross section oxygen is the important absorbing molecule. Three repre-is also shown as it is appreciably different from the total sentative solar zenith angles of 75 °, 60, and 30° are given cross section to about A. The bands may show autoion- in the figures. The oxygen vertical profile is the mean ref-ization structure. James A. R Samson has written: 'Absolute photoionization cross sections of atomic oxygen' -- subject(s): Photoionization of gases, Oxygen 'Dissociative and double photoionization cross sections . The relations between photoionization cross sections and photon radius are obtained on basis of quantum mechanics and the particle-like properties of a photon. The photoionization cross sections of H atom and H-like ions, He atom and He like ions, alkali metal atoms, and Rydberg atoms are calculated using the Size: KB.

Absolute photoionization cross sections of atomic oxygen Download PDF EPUB FB2

The absolute cross section for photoionization of atomic oxygen from the 2p4 3P ground state of O(0) to the 2p3 4S ground state of O(+) has been measured at five narrow wavelength intervals between and nm. The cross section near the 2p3 4S threshold is Mb + or - 7%.Cited by: Absolute cross sections for 2s-electron photoionization of atomic oxygen into the final ionic states O + (2s-1 4 P e, 2 D e, 2 S e, 2 P e) and for the occupation of the O + (3s 2,4 P e) satellite states have been determined experimentally by photon-induced fluorescence spectroscopy.

Comparison of the experimental results with theoretical predictions using multiconfiguration-interaction wavefunctions. Get this from a library.

Absolute photoionization cross sections of atomic oxygen. [James A R Samson; P N Pareek; United States. National Aeronautics and Space Administration.].

Absolute cross sections for 2s-electron photoionization of atomic oxygen into the final ionic states O (2s 14 P e, 2 D e, 2 S e, 2 P e)and for the occupation of the O (3s 2,4 P e) satellite.

Behlen Laboratory of Physics. Total photoionization cross sections of atomic oxygen from threshold to SA G.C. Angel and James A.R. Samson. J I (I •. Comparison of the initial methyl signal with the decrease in precursor signal, in combination with previously measured absolute photoionization cross-sections of the precursors, yields the absolute photoionization cross-section of the methyl radical; σCH3( eV) = ( ± ) × 10−18 cm2 and σCH3( eV) = ( ± ) × 10−18 by: que, the first absolute photoionization cross section measurement for a positive ion was obtained for Ba+ in (Lyon etal).This wasfollowedbythefirstgroup of absolute photoionization cross sections in Ca+ (Lyon et al.

Absolute photoionization cross sections of atomic oxygen book, Sr+ (Lyon, Peart, & Dolder a), K+ (Peart & Lyon ), and Ga+ and Zn+ (Peart, Lyon, & Dolder ).

The absolute cross section for photoionization of atomic oxygen from the 2p4 3P ground state of O(0) to the 2p3 4S ground state of O(+) has been measured at five narrow wavelength intervals between and nm.

The cross section near the 2p3 4S threshold is Mb + or - 7%. Absolute photoionization cross section sigma is derived, yielding sigma=+/ Mb at the maximum of the resonance. In addition, weak contributions to the O((1)D) yield from dissociative ionization originating from molecular singlet oxygen [O(2)((1)Delta(g))] are identified as by: 2.

Keywords: surfaces, SEM, Auger, atomic oxygen, oxidation, sputtering 1. INTRODUCTION Atomic oxygen is one of the main consti-tuents in the atmosphere at low earth orbit. The atomic oxygen oxidation of metals has been the topic of several studies. For the explanantion of the mechanisms see ref.

Interaction of atomic oxygen with various. Finally, the photoionization yield of the iodine atom in its ground state 2P3/2 has been recorded using the synchrotron source and calibrated for the first time on an absolute cross section scale from our fixed nm laser measurement, σiI2P3/2 = 74−23+33 Mb (95% confidence interval).Cited by: The R-matrix method is used to obtain cross-sections for the photoionization of atomic oxygen from the 2s 2 2p 43 P state of O to the 2s 2 2p 34 S o, 2 D o, 2 P o and 2s2p 44 P, 2 P states of O +.

Ea for the 4 S o and the 2 D o O + states are shown to be reliable but the present results reveal considerable discrepancies for the other final ion states, in particular for the 4 P and 2 P states for which an inner Cited by: The experimental knowledge of partial cross-sections for photoionization of nitrogen atom is much less detailed than it is for those of the noble gases, or even lithium or atomic oxygen.

The absolute partial cross-sections are calculated using photoelectron spectroscopy and photoionization mass spectrometry. Abstract. The technique of two-photon excited fluorescence has been used to measure the cross section for the 3p 3 P 2,1,0atomic oxygen.

Excitation was monitored by observing fluorescence at nm from the 3p 3 P 2,1,>3s 3 S 1 transition. Spontaneous Raman scattering from H 2 was used to calibrate the fluorescence collection system. The spatial and Cited by: The absolute single-photoionization cross sections of singly charged nitrogen and oxygen ions have been measured from eV and eV, respectively, by merging a synchrotron-radiation beam from an undulator with a 2 keV ion beam.

a consensus for the best description of the photoionization cross section for neutral atomic oxygen. To this end, it is ad-vantageous to create a single photoabsorption model that is transparent to all atomic data users.

This is most easily accom-plished by formulating an analytical expression that includes all. The fragmentation cross sections for O(\u27+) were then obtained by subtraction of O(,2)(\u27+) cross sections from the known total photoionization cross sections. The results are compared with the previously published measurements.^ The absolute photoionization cross section of atomic oxygen, (sigma)(,0+), was measured at (ANGSTROM).Author: PREM NARAYAN PAREEK.

Indeed, using the same procedure and omitting the atomic oxygen production, we obtained a photoionization cross section of Mb which is about 2 Mb below the corrected value ( Mb). To make sure that the detected photoionized atomic oxygen resulted from the reactivity of water with the fluorine atoms, we have checked that S O + recorded under different experimental conditions was Cited by: 2.

Atomic and Molecular Photoabsorption: Partial Cross Sections is a companion work to Joseph Berkowitz's earlier work, Atomic and Molecular Photoabsorption: Absolute Total Cross Sections, published with Academic Press in In this work Joseph Berkowitz selected the "best" absolute partial cross sections for the same species as included in the companion work.

Abstract. Absolute cross-sections for the K-shell photoionization of Be-like (O 4 +) and Li-like (O 5 +) atomic oxygen ions were measured for the first time (in their respective K-shell regions) by employing the ion–photon merged-beam technique at the SOLEIL synchrotron-radiation facility in Saint-Aubin, -resolution spectroscopy with E/ΔE ≈ (≈ meV, full width at half Cited by: Determination of absolute photoionization cross sections of the phenyl radical Niels E.

Sveum,ab Scott J. Goncherab and Daniel M. Neumark*ab Received 3rd OctoberAccepted 5th December First published as an Advance Article on the web 20th December DOI: /bk.

The absolute photoionization cross section of ground state K+ ions has been measured from the 3p threshold to above the 3s threshold ( eV) by VUV radiation using a merged ion-photon beam set-up. Electronic excitation spectra and absolute differential oscillator strengths (cross sections) have been measured from the visible up to the soft X-ray energy regions ( eV) for the valence-shell photoabsorption of a series of normal alkanes (C₅H₁₂, C₆H₁₄, C₇H₁₆, and C₈H₁₈), single carbon Freons (CFCl₃, CF₂CI₂, CF₃CI, and CF₄), nitrogen dioxide (NO₂) and.

Kirby et al. () calculated the total photoionization cross section for atomic oxygen by compiling and adding partial cross sections, but no measurements were available at that time for wavelengths below about X.

Samson and Pareek () recently reported measurements from the ionization threshold to A. Figure 1 compares the values. G.C. Angel and J.A.R. Samson, Total photoionization cross sections of atomic oxygen from threshold to A, Phys.

Rev. A (). ADS CrossRef Google ScholarCited by: Absolute single photoionization cross-section measurements of Rb 2+ ions were performed using synchrotron radiation and the photo-ion, merged-beams technique at the Advanced Light Source at Lawrence Berkeley National Laboratory.

Measurements were made at a photon energy resolution of ± meV from to eV spanning the 2 P ground state and 2 P metastable state ionization.

Photoionization cross sections for atomic oxygen and nitrogen have been measured from their respective thresholds to Å (for 0) and to R (for N).

Previously unobserved structure in atomic oxygen is reported between and R. Data which extends the atomic nitrogen cross sections to Å and data on the cross section for 02+ production are currently being analyzed. This book presents the results of atomic calculations of subshell and total photoionization cross-sections and asymmetry parameters as a function of photon energies below KeV.

The book provides graphical data for the dipole-length approximation and includes ASCII text data on floppy diskettes for all approximations calculated in the same by: Single and double photoionization cross sections of atomic nitrogen from threshold to 31 A.

Samson & G. Angel,Phys. Rev. A, 42, Table 1. Absolute experimental total photoionization cross sections of N I. Description ( K), ASCII ( K). Total photoionization cross sections of atomic oxygen from threshold to A.

Photoionization cross sections of atomic oxygen and dissociative photoionization cross sections of molecular oxygen were measured from their respective thresholds to angstrom by use of a photoionization mass spectrometer in conjunction with a spark light source. The measured absolute photoionization cross sections of atomic oxygen are tabulated in Table I and are shown in Fig.

3 along with the previous experimental results. The results by Cairns and samson2 were influenced by autoionizing structure in atomic oxygen5s6 and possibly by structure in the excited 02(16) molecular species. REcent laboratory measurements of photoionization cross section s and ion state branching ratios for atomic oxygen, molecular nitrogen and molecular oxygen are combined with theoretical cross sections for soft x-ray absorption and tabulated for use in atmospheric photoionization calculations.the photoionization cross sections of the ground states of Si, P, and S.

Tayal [37] using the R-matrix method (in the LScoupling scheme) calculated the total and partial cross sections for the photoionization of the 3s23p4 3P ground state of the sulfur atom for photon energies from the rst S+(3s23p3 4S) ionization threshold to about 25 eV.