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We observe a complex shape of the Mn2p core level photoemission spectra for Mn in structures of reduced dimensionality such as an ideal monolayer on Ag(001). The Mn2p 3/2 and Mn2p 1/2 spectral intensity is found to split into doublets with separation about 4 and 5 eV, respectively. The data indicate an interpretation in terms of a poorly screened and a well screened final state of the Mn with a core hole. In the monolayer range these two final states have comparable intensities and dominant contributions from atomic 2p 5 3d 5 and 2p 5 3d 6 configurations, respectively. Their intensity ratio is found to be extremely sensitive to the Mn atomic environment and directly reflects the degree of the Mn3d localization, electron correlation and reduction in charge fluctuations. Additional fine structure is clearly visible in high-resolution data for both final state 3d electrons counts and can be assigned to direct and exchange Coulomb interactions of the unfilled core and 3d shells. Slow 3d-charge fluctuations also result in a remarkable three-peak structure of the Mn3s line.

We have studied the structure of epitaxial Mn sandwiches made of ∼ 1 monolayer (ML) Ag/3 ML Mn/Ag(100) by using photoemission methods and low-energy electron diffraction (LEED). Epitaxial films of 3 ML Mn grown on Ag(100) at room temperature (RT) are found to have a body-centered-tetragonal (bct) structure. Yet, upon deposition of ∼ 1 ML Ag, remarkable changes occur in the Mn film. X-ray photoelectron diffraction data reveal that the Mn layer relaxes towards a face-centered-cubic (fcc) structure with the lattice parameter of Ag. This implies an exceptionally large atomic volume for a 3d transition metal as well as unusual electronic and magnetic properties. Actually, an evolution towards more atomic-like behaviour is clearly evidenced by valence band and Mn3s core level photoemission data.

Thin Cu layers have been evaporated at room temperature on Cr films (~ 10 monolayers) deposited on a Cu(001) single crystal. The Crystallographic structure of these sandwiches is analysed by means of low-energy electron diffraction (LEED), angle-resolved ultra-violet photoemission spectroscopy (ARUPS) and X-ray photoemission spectroscopy. The data show that the attenuation of the Cr signal versus Cu deposition is much lower than expected for a uniform film growth. Moreover, the LEED pattern characteristic of the Cr film (made of Cr(110) domains with four different orientations) is visible for Cu coverages as high as 23 ML. This indicates a strong diffusion of the Cu atoms on the Cr film surface and the formation of Cu three-dimensional islands which present, according to ARUPS and X-ray photoelectron diffraction measurements, a highly disordered fcc Crystallographic structure. However the low reactivity of the sandwiches towards oxygen suggests that the whole Cr surface is wetted by at least 1 ML of Cu.