Surface State Modification of XRu$_{2}$Si$_{2}$, X=(La, Ce, Th, U)*

The three-dimensional electronic structures of heavy fermion f-electron materials XRu$_{2}$Si$_{2}$ X=(Ce,U) and their non-f reference materials (X=La,Th) are investigated using photon-dependent angle-resolved photoemission spectroscopy (ARPES). The spatial-dependences of the characterization of UHV-cleaved surfaces combined with guidance from theoretical surface slab calculations clearly identify surface termination related features resulting from cleavage between X-Si layers. Experimental ARPES results are shown for various adsorbate and dosing experiments that suppress or modify the surface states via Si adatom bonding or charge transfer. These results greatly aid the clear identification of the true bulk bands. Differences in the surface state electronice structures between X=(La,Ce, Th, U) arise mainly from different band fillings related to the valence of the bulk X atom.