Projectile charge and energy dependence of titaniumKx rays and satellites following excitation by fast heavy ions

Abstract

High-resolution measurements have been made of Ti $K\ensuremath{\alpha}$ x rays and satellites ($K{L}^{n},n=0\ensuremath{-}4$) following bombardment of thick Ti targets by ${\mathrm{H}}^{+}$, ${\mathrm{He}}^{n+}$, ${\mathrm{Li}}^{n+}$, ${\mathrm{C}}^{n+}$, and ${\mathrm{O}}^{n+}$ ions at energies of 1-5 MeV/amu. A systematic study was made of the effect of projectile atomic number ${Z}_{1}$ and energy ${E}_{1}$ upon the relative intensities, centroid energies, and widths of the various x-ray peaks. The intensity of the satellite structure relative to the diagram lines ($K{\ensuremath{\alpha}}_{1},{\ensuremath{\alpha}}_{2}$) increases with increasing ${Z}_{1}$ for the same-velocity projectile up to ${Z}_{1}=8$. Both the ${Z}_{1}$ and ${E}_{1}$ dependence of these intensities agree reasonably well with a theoretical model described elsewhere. Deviations of peak intensities from theory are discussed. Centroid energies of the peaks increase approximately linearly with ${Z}_{1}$ at a rate of \ensuremath{\sim}1 eV/Z. These energy shifts are compared with Hartree-Fock calculations of the x-ray energies for various members of $M$-shell ($3s \mathrm{and} 3p$) electronic vacancies. Peak widths range from 10 to 37 eV, increasing monotonically with ${Z}_{1}$ for most peaks and increasing monotonically with $n$ for all projectiles. No variation of centroid positions or peak widths was observed for different values of ${E}_{1}$ and fixed ${Z}_{1}$. The observed energy shifts and peak-width variations are discussed in terms of ionization of the $M$ shell, varying distributions of $L$-shell vacancies among the $2s$ and $2p$ subshells, and possible multiplet splittings.