Li K-edge spectra of lithium halides

Abstract

We measured the Li K-edge spectra of lithium halides by means of total electron yield method (TEY), using the soft x-ray Beam Line 2 (BL2) of the compact synchrotron radiation facility at Ritsmeikan University in Japan. In lithium halides, the spectra have a sharp peak at about 60eV and a broad peak at the higher energy side. Various peak structures that appear in the absorption spectra are assigned to the corresponding Li-1s to valence band free orbitals transitions, which have been calculated by the Discrete Variational (DV)-Xalpha molecular orbital calculation method.

Lithium K‐edge XANES spectra for lithium compounds

“…23 -26 In the Li K-edge XANES spectra of lithium halides, the energy of the core exciton peak shifted, depending linearly on the electronegativity of the halogen bonding to the lithium. 17,18 In the present spectra, the core exciton peak does not appear in Fig. 1 exciton peak shifts toward higher energies.…”

“…A shoulder structure was seen at 60.5 eV in Li 2 S and at 61.8 eV in Li 2 O, and the maximum peak of each spectrum was at 65.0 eV in Li 2 S and at 66.8 eV in Li 2 O. In the Li K-edge XANES spectra of the various lithium halides, the peaks appeared at 61.9 eV in LiF, at 60.8eV in LiCl, at 60.5 eV in LiBr and at 60.1 eV in LiIÐ2H 2 O, 17 respectively. These peaks were assigned as the exciton phenomena in which the 1s electron excited by x-rays is bound by the core hole.…”

“…It is difficult to measure the ultra-soft x-ray (below about 70 eV), although the Li K-edge XANES spectra of lithium metal and lithium halides have been reported previously. 10 -15 Some of the present authors 16,17 have reported the Li K-edge XANES spectra of lithium halides using the total electron yield method, and the exciton peaks in the spectra obtained were examined by using the DV-X˛molecular orbital calculation method. 17 However, the spectra of other lithium compounds have not been reported in previous studies.…”

Origin of Low-Energy Peaks in the Ti-K XANES Spectra of SrTiO<SUB>3</SUB> and CaTiO<SUB>3</SUB>

“…Another theoretical approach to XANES spectra is based on molecular orbital (MO) theory. MO-based methods, such as the discrete variational (DV) Xα cluster method, are of potential utility in effectively reproducing XANES features because atomic orbitals (AOs) used as basis functions are localized at constituent atoms [8][9][10][11][12][13][14]. In this paper, we attempted to establish the assignments of low-energy XANES peaks for two typical titanates, SrTiO 3 and CaTiO 3 , using the DV Xα cluster method [15].…”

“…In this paper, we attempted to establish the assignments of low-energy XANES peaks for two typical titanates, SrTiO 3 and CaTiO 3 , using the DV Xα cluster method [15]. This method has been applied successfully to the analysis of XANES spectra for such species as SF 6 , N 2 , and CeO 2 [8][9][10][11][12][13][14].…”