Double-K-shell ionization of Mg and Si induced in collisions with C and Ne ions

Abstract

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 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 calculated 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␣ satellites and hypersatellites and K␤ satellite intensities. Including theoretical predictions in the fitted model is crucial to analyze properly the K␣ hypersatellite region which overlaps the K␤ 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.

Al K-shell x-ray production cross section induced by proton and highly charged heavy ions

“…Besides, the width of the x-ray is broadened due to the distribution of the electron population in multiple inner-shell vacancies. By analyzing the Kα L-shell satellite energy shift of Mg, Al and Si and the results of the multi-configuration Dirac-Fock calculations [9,[25][26][27][28][29][30], one can find that moving one electron from the L-shell causes an energy shift of about 10 eV for the Al K-shell x-ray. Here, the energy shift of 37 eV allows us to estimate that the x-ray at an energy of 1.523 keV originates predominantly from the de-excitation of the multiply ionized Al atoms and about 3-4 L-shell vacancies are produced during the collision of Ar 11+ ions with Al atoms.…”

Multielectron ionization contributions in valence‐to‐core x‐ray emission spectra of third‐row elements

“…When the experimental energy resolution is comparable to the natural lifetime broadening of the characteristic emission lines, rich spectral structure containing multiple ionization satellite and hypersatellite lines is revealed in the x‐ray spectrum induced by ion collision. Within a long lasting and fruitful Ljubljana‐Fribourg collaboration we have successfully applied these satellite/hypersatellite measurements to study inner shell ionization induced in ion‐atom collisions 1–4 . Important experimental developments and rich spectroscopic experience gained throughout these studies could be directly used later on when we moved to synchrotron radiation and used satellite measurements to study photoinduced multiple excitation and ionization 5–9 .…”

“…Within a long lasting and fruitful Ljubljana-Fribourg collaboration we have successfully applied these satellite/hypersatellite measurements to study inner shell ionization induced in ion-atom collisions. [1][2][3][4] Important experimental developments and rich spectroscopic experience gained throughout these studies could be directly used later on when we moved to synchrotron radiation and used satellite measurements to study photoinduced multiple excitation and ionization. [5][6][7][8][9] Compared with ion-induced inner shell ionization governed by direct Coulomb's charged particle interaction, photoinduced multielectron excitations are direct consequence of the electron-electron correlations yielding very low cross sections.…”

Hypersatellite x-ray decay of 3d hollow- K -shell atoms produced by heavy-ion impact

“…The first observation of Kα hypersatellites originating from heavy-ion-atom collisions was reported by Richard et al [22]. This pioneering work was followed by many other studies (see, e.g., [23][24][25][26][27]). Some high-resolution measurements of L and M hypersatellites of mid-heavy and heavy elements were also performed [28][29][30].…”