A calculational approach to electron impact excitation of ions in hot solar plasmas

The cross section requirements are presented for studying UV and X-ray emission spectra associated with active and flare-produced plasmas in the sun's corona. The general approach to the calculation of the distorted wave approximation problem is also given

Kohn-Sham density functional theory calculations of non-resonant and resonant X-ray emission spectroscopy

The accuracy of non-resonant and resonant (resonant inelastic X-ray scattering) X-ray emission spectra simulated based upon Kohn-Sham density functional theory is assessed. Accurate non-resonant X-ray emission spectra with the correct energy scale are obtained when short-range corrected exchange-correlation functionals designed for the calculation of X-ray absorption spectroscopy are used. It is shown that this approach can be extended to simulate resonant inelastic X-ray scattering by using a reference determinant that describes a core-excited state. For this spectroscopy, it is found that a standard hybrid functional, B3LYP, gives accurate spectra that reproduce the features observed in experiment. However, the ability to correctly describe subtle changes in the spectra arising from different intermediate states is more challenging and requires averaging over conformations from a molecular dynamics simulation. Overall, it is demonstrated that accurate non-resonant and resonant X ray emission spectra can be simulated directly from Kohn-Sham density functional theory

The effect of basis set and exchange-correlation functional on time-dependent density functional theory calculations within the Tamm-Dancoff approximation of the X-ray emission spectroscopy of transition metal complexes

The simulation of X-ray emission spectra of transition metal complexes with time- dependent density functional theory (TDDFT) is investigated. X-ray emission spectra can be computed within TDDFT in conjunction with the Tamm-Dancoff approximation by using a reference determinant with a vacancy in the relevant core orbital, and these calculations can be performed using the frozen orbital approxi- mation or with the relaxation of the orbitals of the intermediate core-ionised state included. Both standard exchange-correlation functionals and functionals specifically designed for X-ray emission spectroscopy are studied, and it is shown that the computed spectral band profiles are sensitive to the exchange-correlation functional used. The computed intensities of the spectral bands can be rationalised by consid- ering the metal p orbital character of the valence molecular orbitals. To compute X-ray emission spectra with the correct energy scale allowing a direct comparison with experiment requires the relaxation of the core-ionised state to be included and the use of specifically designed functionals with increased amounts of Hartree-Fock exchange in conjunction with high quality basis sets. A range-corrected functional with increased Hartree-Fock exchange in the short range provides transition energies close to experiment and spectral band profiles that have a similar accuracy to those from standard functionals

The electronic structure of polyaniline and doped phases studied by soft X-ray absorption and emission spectroscopies

The electronic structure of the conjugated polymer, polyaniline, has been studied by resonant and nonresonant X-ray emission spectroscopy using synchrotron radiation for the excitation. The measurements were made on polyaniline and a few doped (protonated) phases for both the carbon and nitrogen contents. The resonant X-ray emission spectra show depletion of the {\pi} electron bands due to the selective excitation which enhances the effect of symmetry selection rules. The valence band structures in the X-ray emission spectra attributed to the {\pi} bands show unambiguous changes of the electronic structure upon protonation. By comparing to X-ray absorption measurements, the chemical bonding and electronic configuration is characterized.Comment: 8 pages, 8 pictures, http://jcp.aip.org/resource/1/jcpsa6/v111/i10/p4756_s

Electronic structure of MgB2_2: X-ray emission and absorption studies

Measurements of x-ray emission and absorption spectra of the constituents of MgB$_2$ are presented. The results obtained are in good agreement with calculated x-ray spectra, with dipole matrix elements taken into account. The comparison of x-ray emission spectra of graphite, AlB$_2$, and MgB$_2$ in the binding energy scale supports the idea of charge transfer from $\sigma$ to $\pi$ bands, which creates holes at the top of the bonding $\sigma$ bands and drives the high-T$_c$Comment: final version as published in PR

Elemental depth profiling of thin film chalcogenides using MeV ion beam analysis

The comprehensive characterisation is one of many technical challenges in the fabrication of photovoltaic devices from novel materials. We show how the application of recent advances in MeV ion beam analysis, providing the selfconsistent treatment of Rutherford backscattering and particle induced X-ray emission spectra, makes a new set of powerful complementary elemental depth profiling techniques available for all thin film technologies, including the chalcopyrite compound semiconductors. We will give and discuss a detailed analysis of a CuInAl metallic precursor film, showing how similar methods are also applicable to other films of interest