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Title: Double 1s shell ionization of Si induced in collisions with 1-3-MeV protons

Abstract

The double 1s ionization of Si induced in collisions with protons was studied by measuring the K x-ray emission of a solid Si target ionized by the impact of 1-3-MeV protons. In order to resolve the hypersatellite contributions corresponding to the radiative decay of the double 1s vacancy state, a high-resolution crystal spectrometer was employed yielding sub-eV energy resolution. From the intensity of the measured hypersatellite lines double 1s ionization cross sections for the studied collisions were determined. Experimental values were compared with the theoretical ones obtained within the independent electron framework employing single electron ionization probabilities calculated with the semiclassical approach. This comparison suggests a sequential two step model for the double 1s ionization which was additionally confirmed by four body classical trajectory Monte Carlo calculations.

Authors:
;  [1];  [2]
  1. J. Stefan Institute, P.O. Box 3000, SI-1001, Ljubljana, Slovenia and Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland)
  2. (ATOMKI), H-4001 Debrecen, P.O. Box 51 (Hungary)
Publication Date:
OSTI Identifier:
20786303
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 72; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevA.72.062704; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; CATIONS; COMPARATIVE EVALUATIONS; CROSS SECTIONS; ELECTRONS; EMISSION SPECTRA; ENERGY RESOLUTION; FOUR-BODY PROBLEM; HYDROGEN IONS; ION-ATOM COLLISIONS; IONIZATION; MEV RANGE; MONTE CARLO METHOD; PROTONS; RADIATIVE DECAY; SEMICLASSICAL APPROXIMATION; SILICON; VACANCIES; X RADIATION; X-RAY SPECTRA

Citation Formats

Kavcic, M., Toekesi, K., and Institute of Nuclear Research of the Hungarian Academy of Science. Double 1s shell ionization of Si induced in collisions with 1-3-MeV protons. United States: N. p., 2005. Web. doi:10.1103/PHYSREVA.72.0.
Kavcic, M., Toekesi, K., & Institute of Nuclear Research of the Hungarian Academy of Science. Double 1s shell ionization of Si induced in collisions with 1-3-MeV protons. United States. doi:10.1103/PHYSREVA.72.0.
Kavcic, M., Toekesi, K., and Institute of Nuclear Research of the Hungarian Academy of Science. Thu . "Double 1s shell ionization of Si induced in collisions with 1-3-MeV protons". United States. doi:10.1103/PHYSREVA.72.0.
@article{osti_20786303,
title = {Double 1s shell ionization of Si induced in collisions with 1-3-MeV protons},
author = {Kavcic, M. and Toekesi, K. and Institute of Nuclear Research of the Hungarian Academy of Science},
abstractNote = {The double 1s ionization of Si induced in collisions with protons was studied by measuring the K x-ray emission of a solid Si target ionized by the impact of 1-3-MeV protons. In order to resolve the hypersatellite contributions corresponding to the radiative decay of the double 1s vacancy state, a high-resolution crystal spectrometer was employed yielding sub-eV energy resolution. From the intensity of the measured hypersatellite lines double 1s ionization cross sections for the studied collisions were determined. Experimental values were compared with the theoretical ones obtained within the independent electron framework employing single electron ionization probabilities calculated with the semiclassical approach. This comparison suggests a sequential two step model for the double 1s ionization which was additionally confirmed by four body classical trajectory Monte Carlo calculations.},
doi = {10.1103/PHYSREVA.72.0},
journal = {Physical Review. A},
number = 6,
volume = 72,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}
  • The K{alpha} x-ray emission spectra of Si bombarded by 1-3-MeV protons were measured with a crystal spectrometer in Johansson geometry, enabling energy resolution below the natural linewidth of the measured K{alpha} line. The K{alpha}L{sup 1} and K{alpha}L{sup 2} (K{alpha}L{sup 1,2}) x-ray satellite lines appearing in these spectra as a result of the radiative decay of atomic states with one hole in the K shell and one or two in the L subshells were precisely measured. The energies and intensities of the main components that could be resolved within the satellite lines are given. It has been demonstrated that the lattermore » do not depend on proton energy and are essentially the same as in photon-induced spectra. The overall K{alpha}L{sup 1} satellite intensity relative to the K{alpha} diagram line has been used to deduce the L-shell ionization probabilities induced in near-central proton collisions. The experimental values were compared to the theoretical values calculated with the semiclassical approximation, with the three-body classical trajectory Monte Carlo model, and the classical binary-encounter-based geometrical model.« less
  • The satellite and hypersatellite K x-ray emission of a thin Mg foil and thick polycrystalline Si target bombarded by 34-MeV C and 50-MeV Ne ions was measured using high-resolution crystal diffractometry. The corresponding projectile reduced velocities v/v{sub K} were 1.09 and 0.92 for C ions and 1.02, 0.86 for Ne ions in case of Mg and Si targets, respectively. An energy resolution of approximately 0.5 eV enabled separation of contributions corresponding to states with different numbers of K- and L-shell vacancies. The relative intensities of satellite and hypersatellite lines were determined by fitting the measured spectra with line shapes calculatedmore » using the GRASP92 computer code. To determine the production yields of initial states from the measured x-ray yields, the total decay schemes of initial states were considered. The decay schemes were also used to determine the relative intensities of components contributing to the observed K{alpha} satellites and hypersatellites and K{beta} satellite intensities. Including theoretical predictions in the fitted model is crucial to analyze properly the K{alpha} hypersatellite region which overlaps the K{beta} satellites. The initial-state production yields were then used to determine the L-shell ionization probabilities and the double- to single-K-shell ionization ratio corresponding to the four investigated collisions. The experimental values were compared to the theoretical predictions obtained within the independent electron model using single-electron ionization probabilities calculated by the three-body classical trajectory Monte Carlo (CTMC) method. Since the targets used were thick enough, the equilibrium projectile charge-state distributions in the solid media were assumed. While for the double- to single-K-shell ionization ratios a satisfactory agreement was observed between the CTMC predictions and our experimental results, the L-shell ionization probabilities were found to be overestimated by the CTMC calculations by a factor of about 2.« less
  • Absolute {ital K}-shell ionization cross sections have been measured for thin targets of Si, P, S, K, Ca, Zn, and Ga using carbon ions between 1.0 and 6.4 MeV and protons of 1 and 2 MeV. The dependence of x-ray production cross sections on target thickness was determined. The experimental results are compared to the semiclassical approximation (Laegsgaard, Andersen, and Lund in 3 Proceedings of the Tenth International Conference on the Physics of Electron and Atomic Collisions, Paris, 1977, edited by G. Watel (North-Holland, Amsterdam 1977)), to the theory for direct Coulomb ionization of the 1{ital s}{sigma} molecular orbital (Montenegromore » and Sigaud, J. Phys. B. 18, 299 (1985)), to the perturbed stationary-state approximation with energy-loss, Coulomb, and relativistic corrections (ECPSSR) (Brandt and Lapicki, Phys. Rev. A 23, 1717 (1981)), and to the modification of the ECPSSR approximation (MECPSSR) (Benka, Geretschlaeger, and Paul, J. Phys. (Paris) Suppl. 12, C9-251 (1987)). The results for carbon ions are also compared to the statistical molecular orbital theory of inner-shell ionization for symmetric or nearly symmetric atomic collisions (Mittelman and Wilets, Phys. Rev. 154, 12 (1967)).« less
  • Single and double [ital K]-shell vacancy production and [ital K]-[ital K] electron-transfer cross sections have been measured in the limit of zero target thickness for Fe and Ni induced by 1.25--4.70 MeV/amu [sup 28]Si and [sup 32]S ions. The fluorescence yield [omega][sub [ital k]] for Fe and Ni at x-ray emission was determined from the measured energy shifts of target [ital K] x rays, the intensity ratios of [ital K][beta] and [ital K][alpha] and using the statistical scaling procedure of Larkins [J. Phys. B 4, L29 (1971)]. The single-electron-transfer cross sections are compared with the atomic-orbital-expansion model (AO) of Fritschmore » and Lin [Phys. Rep. 202, 1 (1991)], and the semiempirical perturbed-stationary-state (PSS) approach of Lapicki and McDaniel [Phys. Rev. A 22, 1896 (1980)]. The AO calculations show excellent agreement with the single [ital K]-[ital K] transfer cross sections. This model also explains the double [ital K]-[ital K] transfer data quite well although it underestimates slightly the measured values. The direct [ital K]-shell ionization cross section data are compared with the ECPSSR (perturbed-stationary-state theory with energy-loss, Coulomb deflection, and relativistic corrections) calculations.« less
  • High-resolution K{alpha} x-ray spectra of Ca, Cr, and Fe induced by (0.7{endash}1.5)-MeV protons and of Ti induced by (0.7{endash}4)-MeV protons were measured by a flat crystal spectrometer. From the relative yields of the KL{sup 1} satellites, which are the result of multiple inner-shell ionization, the average L-shell ionization probabilities in near-central collisions were determined. The effects of the rearrangement of the inner-shell holes prior to the K x-ray emission and the changes of the fluorescence yields due to the multiple ionization were taken into account in the evaluation of the ionization probabilities. The direct Coulomb ionization probabilities in the near-centralmore » collisions were determined from the relative yields of the KL{sup 1} satellites after subtracting the shake contribution. The values obtained were compared with semiclassical approximation calculations exploiting relativistic hydrogenic and Hartree-Fock wave functions. The importance of a realistic atomic description using Hartree-Fock wave functions was demonstrated. {copyright} {ital 1997} {ital The American Physical Society}« less