  We demonstrate using inelastic scanning tunneling spectroscopy (ISTS) and
simulations based on density functional theory that the amplitude and sign of
the magnetic anisotropy energy for a single Fe atom adsorbed onto the Pt(111)
surface can be manipulated by modifying the adatom binding site. Since the
magnitude of the measured anisotropy is remarkably small, up to an order of
magnitude smaller than previously reported, electron-hole excitations are weak
and thus the spin-excitation exhibits long lived precessional lifetimes
compared to the values found for the same adatom on noble metal surfaces.
