[en] We report on UHV photoemission studies of Yb metal using synchrotron radiation in the photon energy range 25< h upsilon<180 eV, whereby maximum surface sensitivity can be reached. The 4f photoemission spectrum shows a quadruplet structure due to a superposition of two 4f spin orbit doublets. One doublet has a very symmetric linashape and an extremely narrow lifetime linewidth 2 γ approximately equal to 0.013 eV. We attribute it to bulk emission. The other doublet exhibits almost symmetric lines with a much larger lifetime linewidth 2 γ approximately equal to 0.43 eV. It has also a larger binding energy by 0.6-+0.03 eV. We attribute this as being due to chemically bound Yb atoms located at the surface. We discuss the implications of these findings for recent high resolution photoemission studies of Rare Earth (RE) metals and their analysis. (orig.)