It is well known that the conductivity of metal nanowires decreases with the wire diameter. This size effect was first studied for metal thin films when the film thickness approaches the electron mean free path. Fuchs & Sondheimer (FS) pointed out that the external surface scattering of the electrons contributes to the conductivity decrease. https://parisnaturalfoodes.shop/product-category/gold-standard-casein-creamy-vanilla/