Inthepastfewdecades, greatprogresshasbeenmadeinthe?eldofdynamical interactions of photons and charged particles with surfaces. Developments in this ?eld have largely been driven by technological advances. Foremost, the preparation and characterization of atomically ?at surfaces has opened up opportunities to precisely and reproducibly investigate surface structure and dynamics in unprecedented detail. An equally important advance represents the availability of new sources for projectiles interacting with and probing surfaces. Third-generation s- chrotron sources provide high-brilliance photon...