So you mean what happens if your material goes nano (from a bulk material to a nano-material with identical composition etc)? Well what may happen depending on the size is that the mean free path of the photoelectrons is affected: Due to the scattering at the boundaries between the individual particles the mean free path will be smaller, and your surface sensitivity will be enhanced. Furthermore a broadening of the photoelectron peaks may be expected. The crucial point is that the effects are dependent on the kinetic energy of the photoelectrons, and thus transitions with larger energy may behave different from those with smaller energy.