Noble optical reflectivity

NIRMS = noble-gas-ion reflection mass spectrometry OSEE = optically stimulated exoelectron emission PES = photoelectron spectroscopy PhD = photoelectron diffraction SIMS = secondary ion mass spectroscopy UPS = ultraviolet photoelectron spectroscopy ... 

Structural, reactivity, and optical properties of noble metal clusters attracted theoretical [47, 49, 104, 166-179] and experimental studies [178-192] over the years because of their relatively simple electronic nature in comparison with transition metals and their similarity to -sheU alkali metals. This is particularly the case for the Ag atom with a large s-d gap in contrast to the An atom. In the latter case, the s-d gap is considerably smaller, because the relativistic effects play an essential role— for example, strongly influencing the energy of an i-orbital. These differences in electronic structure are also reflected in the... 

The first example concerns the ER effect, an effect which is always present in optical studies of electrode surfaces but which was first recognised using reflectance spectroscopy. It arises from the fact that, even in the absence of any surface reaction, there is a layer at the electrode surface (typically less than 0.1 nm thick) that does not have the same optical properties as the bulk electrode, and that the optical properties of this layer are potential dependent. There are now several theories to account for the ER effect the simplest, and one that accounts fairly well for the behaviour observed at noble metal electrodes, is due to McIntyre Aspnes [23]. It assumes that the optical properties of the metal can be split into two contributions, one from bound electrons and the other from free electrons. Whilst the bound electron contribution is assumed to be independent of the electrode potential, the free electron contribution changes with the surface charge density, and thus the potential. For normal incidence it is shown that... 

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