Binding and Field Desorption of Individual Tungsten Atoms

摘要: The binding energy of individual tungsten atoms on different planes a crystal, heretofore inaccessible to measurement, has been explored by field desorption at 20°K. Tunneling, rather than evaporation over Schottky saddle, is the limiting step under these conditions. appropriate relations between and atomic are derived tested establishing for 6.1 V / A. Desorption measurements single adatoms lead following energies: (110), 5.3 eV; (211), 7.0; (310), 6.7; (111), 6.0; (321), (411), 6.2. On low index such as agreement with energetics estimated from Morse Lennard‐Jones potentials reasonable. For rougher surfaces, however, experimental quantities significantly smaller expected, suggesting fundamental limitation potentials. Comparison energies activation diffusion (211) (321) also leads view that fluctuations in position lattice play an important role surface migration.