X-Ray Emission Cross Sections following Charge Exchange by Multiply-Charged Ions of Astrophysical Interest
State selective nl-electron capture cross sections are presented for highly charged ions with Z = 6-10 colliding with atoms and molecules. The energy range investigated was from 1 eV/amu (v = 0.006 a.u.) to 100 keV/amu (v =2.0 a.u.). The energy dependence of the l-level populations is investigated. The K-shell x-ray emission cross sections are determined by using the calculated state-selective electron capture results as input and then applying hydrogenic branching and cascading values for the photon emission. A major shift in the line emission from being almost solely Lyman-{alpha} transitions at the highest collisions energies to strong high-n to 1s transitions at the lowest energies is observed. The calculated cross sections are in reasonable accord with measurements made by Greenwood et al, Phys. Rev. A 63, 062707 (2001), using O{sup 8+} and Ne{sup 10+} on various targets at 3 keV/amu. The calculations are also in accord with x-ray emission cross section data obtained on the EBIT machine at LLNL where O{sup 8+} and Ne{sup 10+} high resolution measurements were made at a temperature of 10 eV/amu for a series of targets with varying ionization potentials. The Ne{sup 10+} data clearly shows the contribution from multiple capture followed by Auger autoionization in the line emission spectra. Our calculated line emission cross sections are used to provide an ab initio determination of the soft x-ray spectrum of comet C/Linear 1999 S4 that was observed on the Chandra X-ray Observatory. The calculations show that the spectrum is due to charge exchange of the neutral gases in the comet's coma with the ions of the slow solar wind.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 898590
- Report Number(s):
- UCRL-JRNL-215642; TRN: US0701684
- Journal Information:
- Physical Review A, vol. 73, N/A, September 23, 2005, pp. 022723, Journal Name: Physical Review A, vol. 73, N/A, September 23, 2005, pp. 022723
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ATOMS
AUTOIONIZATION
CHARGE EXCHANGE
COMETS
CROSS SECTIONS
ELECTRON CAPTURE
EMISSION SPECTRA
ENERGY DEPENDENCE
ENERGY RANGE
GASES
IONIZATION POTENTIAL
K SHELL
PHOTON EMISSION
RESOLUTION
SOLAR WIND
TARGETS