Everyday application of XPS allows to unravel with quite simple procedures the elemental and chemical composition of materials surface in a quantitative way. Core and valence band spectra analyses do contain structural information as well : to gather it, high resolution analysis and sometimes study of reference materials are necessary. This will be demonstrated with the determination of the good-or-bad assembling property of some silane molecules with different hydrocarbon chain length deposited from a solution onto TiO@sub 2@ single crystals ; a model of the -Si-O-Ti-O- interfacial layer will be presented. While XPS and UPS synchrotron photoemission valence band analysis remain still qualitative for the determination of structural order, we will show that high resolution electron energy loss spectroscopy[( HR)EELS] can been successufully used to evaluate the crystalline domain size of alkane thiols layers assembled on gold surfaces ; indeed, the measure of the angular distribution of the scattered electrons corresponds to a diffraction experiment. With contributions of R. Magnée, Ch. Grégoire and A.-S. Duwez