K-MM radiative-Auger transition probability calculations for Ca, Ti and Cr

Abstract

The K-MM radiative-Auger transition probabilities for Ca, Ti and Cr were calculated using time-dependent perturbation theory. The atom plus the free radiation field are considered as being one system and the transition of one state of the atom to another results from the interaction between components of this system. The perturbing Hamiltonian is taken as the sum of the interaction between the electrons participating directly in the process and their interaction with the radiation field. Under this approach, the radiative-Auger process is described considering second-order terms in time-dependent perturbation theory series. The calculations were performed using screened hydrogenic wavefunctions to describe the state of the atom. The results obtained are compared with recent experimental data and other theoretical calculations.

High-resolutionKMMradiative Auger x-ray emission spectra of calcium induced by synchrotron radiation

“…Kβ 1,3 yield ratio consistent values of 0.025(7) and 0.030 (12) were found from the fits of the spectra acquired at 4088 eV and 5493 eV.…”

“…Therefore the latter contributions were not taken into consideration in the present work. , the theoretical radiative field transition rates from Baptista [12] are shown for the 3p −2 np (n ≥ 4) RA SU transitions (dotted sticks) and 3p −2 ǫp RA SO transitions (exponential tails).…”

“…The first column of the table lists all KMM shake-up RA dipole transitions allowed by the selection rules proposed by Bloch [1] and Aberg [7]. The energies of the corresponding transitions calculated with the DV-Xα for solid [10] and radiative field methods for atomic Ca [12] are given in the 3rd and 4th column, respectively. Finally, the RA edge energies derived in [24] from the LMM Auger transition energies reported by Larkins [47] are also listed (5th column).…”

“…On the other hand, for a given initial inner-shell vacancy, the relative RA x-ray emission yield increases with the principal quantum number of the electrons involved in the transition because of the higher shake probability characterizing the less bound outer shell electrons. However, large discrepancies exist between the existing experimental data and the available shake-off (up) [7], configuration interaction (CI) [9], DV-X α [10], and radiative field [11,12] calculations for the relative intensities as well as for the RA x-ray emission spectral shapes.…”

“…KMM RA transitions which appear on the low energy tail of the Kβ 1,3 diagram line were chosen because they are the strongest radiative Auger transitions decaying K-shell vacancies. For the choice of the target, preference was given to Ca because for this element different theoretical predictions for the KMM RAE yields were available [8,12]. On the other hand, among the few existing experimental data concerning the KMM RA transitions of Ca, none of them was obtained using SR for the target excitation.…”