The controlled-valence properties of ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{FeO}}_3$ and ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{MnO}}_3$ are studied by means of soft-x-ray absorption spectroscopy. A comparison between the transition-metal 2p spectra and atomic-multiplet calculations is used to determine the 3d count. The O 1s spectrum is used to characterize changes in unoccupied states that contain oxygen p character. The results indicate that the holes induced by substitution for both series are located in states of mixed metal 3d–oxygen 2p character. The ground state of ${\mathrm{LaFeO}}_3$ is mainly 3${\mathit{d}}^5$ and becomes 3${\mathit{d}}^5$L (where L denotes a ligand hole) in the ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{FeO}}_3$ series for low Sr concentration. The main component of the ground state of ${\mathrm{LaMnO}}_3$ is 3${\mathit{d}}^4$ and becomes a mixture of 3${\mathit{d}}^3$ and 3${\mathit{d}}^4$L in the ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{MnO}}_3$ series. The trends in controlled- valence properties of similar oxides across the transition-metal series can be rationalized within the framework of the Zaanen-Sawatzky-Allen model.

The electronic structure of ${\mathrm{La}}_{\mathit{x}}$ ${\mathrm{Sr}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{TiO}}_3$ has been studied by photoemission and x-ray absorption spectroscopy. Electron doping through La substitution induces a new photoemission feature of Ti 3d character within the band gap of ${\mathrm{SrTiO}}_3$; the Fermi level is located near the bottom of the conduction band of ${\mathrm{SrTiO}}_3$. The experimental results are incompatible with the rigid-band behavior predicted by one-electron band theory or Hubbard-model calculations.

Creating or connecting together large organic molecules, as polycyclic aromatic hydrocarbons (PAH), by chemical reactions readily on surfaces is the first step to a true advance in the field of molecular electronics. On-surface synthesis can be regarded as an efficient means to build new molecular species by using bottom-up strategies. Recently, a collection of different reactions leading to large tailor-made organic molecules on single-crystal metal surfaces has been reported. The fundamental mechanisms controlling these reactions can be investigated from a surface science perspective. This discipline skillfully combines the use of characterization techniques at the nanoscale, with single-crystal metallic surfaces able to catalyse these reactions. We present a tutorial review that highlights the relevance of the new bottom up strategies and classifies most of the different molecular on-surface reactions involving aromatic organic molecules that have been published up to date.

The differences between L₃ and L₂ edges of 3d and 4d transition metal complexes and compounds in octahedral symmetry are discussed. The main origin of these differences are the multiplet effects due to the coupling of the 2p core wave function and the 3d and 4d valence wave functions. The 3d and 4d spin–orbit coupling is a second origin of difference. For 3d systems the multiplet effects dominate all other interactions and the L₃ and L₂ edge are completely mixed and reordered. For 4d systems the core hole spin–orbit coupling is large and the L₃ and L₂ are separated by about 100 eV with a ratio close to 2:1. The differences between the L₃ and L₂ edge originate from the weight transfer between the t_2g and e_g peaks due to the multiplet effect. This weight transfer is about 25% for the L₃ edge and about 5% for the L₂ edge, which implies that for a comparison to single‐particle calculations the L₂ edge is preferable to use. Partly filled 4d systems are low‐spin and the occupation of the t_2g states implies a decrease of the first peak. This decrease is stronger for the L₂ edge, implying an increase in the L₃:L₂ ratio. For 4d⁵ systems transitions to the t_2g hole are only possible at the L₃ edge due to the combined effects of 4d spin–orbit coupling and the dd multiplet effects.