Multi-atom resonant photoemission in transition metal chlorides

Recently multi-atom resonances in photoemission of transition metal oxides were observed by Kay et al. [A. Kay, E. Arenholz, S. Mun, F.J. Garcia de Abajo, C.S. Fadley, R. Denecke, Z. Hussain, M.A. Van Hove, Science 281 (1998) 679]. We present the results of a systematic study of multi-atom resonant photoemission in transition metal chlorides. We measured the intensity of the chlorine 2p photoelectron line excited around the metal 2p photoabsorption edge of the transition metal compounds MnCl2, CrCl2, and VCl2 as well as of the ionic solid KCl. Our experimental results show that the intensity of Cl 2p photoelectron lines enhance by about 29% for MnCl2, 21% for CrCl2, 17% for VCl2 and 11% in the case of KCl at the metal 2p photoabsorption edge. We ascribe the systematic decrease of the magnitude of this effect, going from MnCl2 to KCl, to the extension of the excited metal 3d wavefunction and, as a consequence, decrease of the overlap between the 3d and 2p atomic orbitals.