Relativistic many-electron calculations of Cr3+ L2,3-edge x ray absorption near-edge structures for Cr3+:α-Al2O3 and α-Cr2O3 and magnetic circular dichroism of Cr3+L2,3-edge x ray absorption near-edge structures for Cr3+:α-Al2O3

Abstract

We performed first-principles calculations for Cr3+ L2,3-edge x ray absorption near-edge structures (XANES) of Cr3+:α-Al2O3 (ruby) and α-Cr2O3 and magnetic circular dichroism (MCD) of Cr3+ L2,3-edge XANES of ruby using a relativistic multielectron method. In order to investigate the lattice relaxation effects for ruby, theoretical studies were carried out using the three types of model clusters, including the lattice relaxation effects. These theoretical XANES spectra for both ruby and α-Cr2O3 well reproduced the experimental XANES spectra. The lattice relaxation effects on the XANES spectra for ruby were very small, while the results of configuration analysis of the many-electron wave function indicated that the mixing between L2 and L3 edges was significantly large in Cr3+ L2,3-edge XANES spectra for both ruby and α-Cr2O3. In addition, XANES spectra showed that the L3-edge component significantly mixed in the L2-edge peaks, while the L3-edge component also significantly contributed to the intensity of L2-edge. The theoretical MCD spectra for ruby also well reproduced the experimental one. We also investigated the validity of the sum rules quantitatively by comparing the magnetic moments calculated from the theoretical spectra using the sum rules and those calculated directly from the explicit many-electron wave functions. The orbital moments by both methods were almost zero, and the spin moments had 10% difference between these methods. The results of the configuration analysis indicated that the magnitude of the mixing between L2 and L3 edges could be the major cause of this discrepancy.

Direct Observation of Cr3+ 3d States in Ruby: Toward Experimental Mechanistic Evidence of Metal Chemistry

“…We note that our XAS simulation matches the experimental data to a considerable higher degree of accuracy than previous presented results. 39,72 In fact, Gaudry et al used an identical scaling of F dd 2 and F dd 4 , being 56% of the Hartree–Fock values (70% of the ionic Cr 3+ case; the nephelauxetic ratio being 0.7). Such identical scaling was also applied in one of the spectra of Supporting Information, Figure S4, and yields a similar curve as the one presented by Gaudry et al These parameters are able to simulate the chromium 2p XAS spectrum of, for example, α-Cr 2 O 3 , 39 but not that of ruby, confirming that the odd F dd 2 / F dd 4 scaling relates to low-concentrated Cr 3+ in ruby.…”

First‐Principles Study of Chromium Defects inα‐Al2O3: The Origin of Red Color in Ruby

“…Afterward, Ogasawara and coworkers extensively examined the entire multiplet structure of ruby by using DVME method with various corrections and their calculated results provide better agreement with the experiment than their original study. [ 12–15 ]…”

“…Afterward, Ogasawara and coworkers extensively examined the entire multiplet structure of ruby by using DVME method with various corrections and their calculated results provide better agreement with the experiment than their original study. [12][13][14][15] Regarding ligand-field theory based on cubic-field approximation, the U and Y bands are assigned to the transitions from the ground state t 3 2g," 4 A 2g to the excited states t 2 2g," e g," 4 T 2g and t 2 2g," e g,"…”

Crystal-field Paschen-Back effect on ruby in ultrahigh magnetic fields

“…The most well-known example is the R lines of ruby [13][14][15][16]. Many spectroscopic works on ruby have been done for more than half century, motivated by the scientific interests [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] as well as its applications to a solid-state laser and pressure gauge [28][29][30][31][32][33]. The optical transitions of ruby stem from the Cr 3+ impurities in α-Al 2 O 3 , where Cr 3+ ions are subjected to the cubic crystal field of the octahedrally coordinated O 2− ions.…”