We present a systematic theoretical study on angular and polarization properties of the prominent $4f\to 3d$ characteristic lines in Ni- to Ga-like gold ions (${\mathrm{Au}}^{51+}$ to ${\mathrm{Au}}^{48+}$), excited by electron impact over a wide range of impact energies. Calculations are performed within the framework of density matrix theory, utilizing the multiconfigurational Dirac-Hartree-Fock and relativistic distorted-wave approaches to obtain excitation energies, cross sections, alignment parameters, and, particularly, the angular anisotropy and linear polarization of the emitted lines. Our results reveal that these lines are strongly anisotropic and linearly polarized, at a level readily observable with current x-ray spectrometers. These characteristics exhibit a pronounced dependence upon the impact energy, peaking near 4 keV, and a strong sensitivity to the ion charge state: lines of ${\mathrm{Au}}^{51+,49+}$ ions are significantly more anisotropic and polarized than those from ${\mathrm{Au}}^{50+,48+}$ ions at comparable energies. The distinct dependencies on electron energy and ion charge state suggest that accurate measurements of these line features could provide a potential diagnostic for determining electron energy and ion species in high-temperature fusion gold plasmas.

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• Atomic & molecular collisions
• Atomic spectra
• Electron correlation calculations for atoms & ions
• Electronic excitation & ionization
• Electronic transitions
• Spontaneous emission
• Ions
• Polarization
• Hartree-Fock methods
• Quantum chemistry methods