Surface states generated by chemical or electrochemical treatments seem to be the latter
source of limitation for superconducting cavities. How does it affect superconducting RF
properties of the material, is this effect due to the morphology of the surface or its
local chemical composition ? As an attempt to answer to these questions, Nb samples were
submitted to various surface treatment, and studied systematically with various surface
techniques either from the morphological point of view (x-rays reflection, profilometry,
tunnel microscopy) as from the chemical composition of the very surface point of view
(TOF-SIMS, ESCA). In parallel, some attempts to develop new chemical etching are shortly
described.
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