Many-body calculation of the core hole spectra of PdCO

Abstract

To investigate the dependence of ligand (adsorbate) core hole spectra on the electronic structure of the metal substrate, we performed ab initio 2h1p and 2h2p/3h2p CI calculations of the core hole spectra of the linear PdCO molecule using an extended basis set. The main line is the one-hole state and takes a much larger intensity than for NiCO and NiN 2 but still smaller than for free CO. As in the case of NiCO and NiN 2, also for PdCO the π charge transfer (CT) shakeup satellite of a small intensity is obtained near the main line peak. The most striking spectral feature of PdCO which differs from NiCO and NiN 2 is the absence of the 5 eV giant σ shakeup satellite in the carbon spectrum. In the oxygen spectrum the corresponding satellite of a small satellite intensity, is shifted toward the higher energy (around 8 eV). However, with an increase of the bond length this satellite also disappears. As in the case of NiCO, the π to π * shakeup satellites are obtained around 9 eV for both carbon and oxygen spectra. These dramatic spectral feature changes are explained in terms of the different degree of the dσ-s hybridization and s-dσ promotion in the local metal configuration in the ground and ionized states. We point out the possibility that the DES spectrum becomes similar to the AES spectrum in the spectator Auger decay energy region even when initial core hole state differs.