Journal of Electron Spectroscopy and Related Phenomena 137–140 (2004) 357–361 Theory of resonant X-ray emission spectroscopy in Sc halides Masahiko Matsubara a,∗ , Takayuki Uozumi b , Akio Kotani c,d a Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan b College of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan c RIKEN/SPring-8, 1-1-1, Mikazuki-cho, Sayo-gun, Hyogo 679-5148, Japan d Photon Factory, IMSS, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan Available online 18 March 2004 Abstract Theoretical calculations of the Sc 2p → 3d → 2p resonant X-ray emission spectroscopy (RXES) in ScF 3 , ScCl 3 and ScBr 3 are performed with a ScX 6 (X = F, Cl and Br) cluster model. Effects of incident photon polarization, intra-atomic multiplet coupling and interatomic hybridization are taken into account. We pay attention to the intensity ratio of the RXES spectra arising from nonbonding states, which has mainly two peaks due to the crystal field splitting. From the change of the spectral intensity in RXES we can find that the highest energy structure of the main peaks in X-ray absorption spectroscopy (XAS) varies from almost pure e g state to the e g and t 2g mixed state according to the strength of multiplet effect and hybridization effect. © 2004 Elsevier B.V. All rights reserved. Keywords: Resonant X-ray emission; Sc halides; Incident photon polarization; Nonbonding state; Multiplet effect; Hybridization effect 1. Introduction Resonant X-ray emission spectroscopy (RXES) is a use- ful tool to analyze electronic structures of transition metal compounds due to the recent development of high bright- ness synchrotron light sources [1–4]. In RXES a core elec- tron is excited near the threshold by an incident photon, and then the excited state decays by emitting an X-ray photon. Hence, the whole process of RXES is described by a coher- ent second order optical process and the intermediate state of RXES corresponds to the final state of X-ray absorption spectroscopy (XAS) [5,6]. The polarization dependence in RXES is a new interest- ing topic [7–10]. Recently we studied the 2p → 3d → 2p RXES of TiO 2 and ScF 3 (3d 0 systems) in “polarized” and “depolarized” configurations, and showed a drastic polar- ization dependence both theoretically and experimentally [8]. The “polarized” configuration is the case where the polarization vector of the incident photon is perpendicular to the scattering plane and the “depolarized” configuration is the case where it is parallel to the scattering plane. In ∗ Corresponding author. Present address: Institut de Physique et Chimie des Mat´ eriaux de Strasbourg, 23 rue du Loess, BP43 67034 Strasbourg Cedex 02, France. E-mail address: matubara@issp.u-tokyo.ac.jp (M. Matsubara). both configurations the scattering angle is fixed to 90 ◦ , and the polarization of the emitted photon is not detected. More recently, we have extended the study to 3d 1 , 3d 2 and 3d 3 systems TiF 3 , VF 3 and Cr 2 O 3 [10]. In the present paper we calculate the RXES spectra for 3d 0 Sc compounds: ScF 3 , ScCl 3 and ScBr 3 . Few systematic study of electronic states with the change of ligand ions for these materials has so far been made. Spectral calculations of RXES and XAS are performed with a ScX 6 (X = F, Cl and Br) cluster. In the 3d 0 systems the RXES spectra has strong incident photon polarization. The spectra obtained in the polarized configuration has mainly three structures: elastic peak, strong inelastic scattering peak and weak in- elastic structures between the elastic and strong inelastic peaks, whereas the spectra obtained in the depolarized configuration consist of only the weak inelastic scattering spectra. In the previous papers [8,10] we concentrate on the behavior of elastic peak and strong inelastic peaks. But here we pay attention to the weak inelastic structure, which is mainly split into two peaks due to the crystal field energy, and its behavior of the relative intensity of these two peaks. From the analysis we can find that the highest energy structure of the main peaks in XAS varies from almost pure e g state to the e g and t 2g mixed state according to the magnitude of the multiplet effect and hybridization effect. 0368-2048/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.elspec.2004.02.112