Ultra-high-accuracy X-ray spectroscopy of transition metal oxides and rare earths

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K- and L-shell theoretical fluorescence yields for the Fe isonuclear sequence

Publication . Pinheiro, Daniel; Fernandes, André; Godinho, César; Machado, Jorge; Baptista, Gonçalo; Grilo, Filipe; Sustelo, Luís; Sampaio, Jorge M.; Amaro, Pedro; Leitão, Roberta G.; Marques, José P.; Parente, Fernando; Indelicato, Paul; de Avillez, Miguel; Santos, José Paulo; Guerra, Mauro; DF – Departamento de Física; LIBPhys-UNL; Elsevier

In this work, we present K- and L- shell fluorescence yield values of the full isonuclear sequence of Fe ions, using a state-of-the-art multiconfiguration Dirac–Fock approach. These results may be of importance for spectral fitting and plasma modeling, both in laboratory and astrophysical studies, where Fe is an important benchmark element. The K-shell fluorescence yields were found to be very similar up to the removal of 14 electrons.

2023-02Artigo científico

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Angular distribution of characteristic X-rays following electron impact ionization

Publication . Pinheiro, Daniel; Amaro, Pedro; Machado, Jorge; Guerra, Mauro; Santos, José Paulo; DF – Departamento de Física; LIBPhys-UNL; Elsevier

In this paper, we present a theoretical study of the X-ray fluorescence emission after vacancy of K-shell due to electron impact ionization. In particular, we focus on the angular distributions of the characteristic Kα emission lines following this process. Rh was chosen for the analysis since it is a common element in X-ray tube anodes. In this analysis we also considered some elements along the period-4, i.e., Ni, Cu and Co as case-studies. In doing so, we studied the magnetic sub-level population of the ionized states, which is directly related to the angular distribution of the emission. A relative low angular distribution for the Kα emission of Rh of 0.5% was observed, which makes the assumption of isotropic emission correct for most studies. Moreover, a comparison with the respective angular emission for adjacent elements in the fourth period of the periodic table shows that this isotropy is attributed to a small total angular momentum of the resulting configurations after ionization, as well as to opposite angular distributions of the various transitions, which average to a maximum of 0.7% angular asymmetry in Ni.

2023-02Artigo científico

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Entidade financiadora

Fundação para a Ciência e a Tecnologia

Programa de financiamento

Concurso para Financiamento de Projetos de Investigação Científica e Desenvolvimento Tecnológico em Todos os Domínios Científicos - 2017

Número da atribuição

PTDC/FIS-AQM/31969/2017