The morphology of the Ag(110) surface after ${\mathrm{Ar}}^{+}$ ion sputtering has been studied by a variable temperature scanning tunneling microscope. For ion energies greater than 800 eV and in the temperature range $270<\mathrm{}{T}_S<320\mathrm{}\mathrm{K}$ (where $T_S$ is the sputtering temperature), a peculiar ripple structure well aligned along the $〈1\overline{1}0〉$ direction and independent of the ion beam angle has been observed. A simple model of this effect, based on the anisotropy and on the temperature hierarchy of the Ag adatom and vacancy surface diffusion, explains the observed features.

The mechanism of strain relief for compressively stressed Ag layers epitaxially grown on Pt(111) is studied by scanning tunneling microscopy. The strain in the compressed commensurate (1×1) Ag monolayer on Pt(111) is relieved in the bilayer by the formation of two weakly incommensurate structures: the metastable striped incommensurate phase, which converts into a trigonal network of domain walls upon annealing. This network is a general case for isotropic strain relief realized by the crossing of domain walls. The introduction of a phase shift of one set of domain walls allows the system to account for the energy difference of fcc and hcp stacking. The stability of unidirectional via isotropic strain relief and the respective structures of domain walls is generally discussed for surface reconstructions and metal epitaxy of hexagonal-close-packed surfaces.

The European Research Council has recently funded HOLMES, a new experiment to directly measure the neutrino mass. HOLMES will perform a calorimetric measur

Nucleation has been studied on atomic scale for Ag deposition on a Pt(111) surface at low temperature (50-120 K) by means of variable-temperature scanning tunneling microscopy. From island density versus coverage data, the transition from the initial steps of nucleation to growth and coalescence has been studied as a function of temperature. The data show that dimers are stable nuclei for $T\le 110$ K, which facilitates quantitative comparison with rate equations from nucleation theory. The migration barrier $E_m=157\mathrm{}\pm 10$ meV is determined for Ag adatoms on Pt(111) and compared with theoretical values.

Surface morphology of a Cu(110) crystal, generated by ion sputtering, has been investigated by scanning tunneling microscopy. Different from recent theoretical predictions and experimental results, normal sputtering produces a well defined ripple structure whose wave vector rotates from $〈001〉$ to $〈1\overline{1}0〉$ by increasing the substrate temperature. Off-normal sputtering at low temperature (180 K) generates ripples whose orientation depends on both ion direction and surface azimuthal orientation. These results are described by a continuum equation which includes both surface curvature dependent erosion terms and diffusion terms accounting for surface anisotropy and Ehrlich-Schwoebel barriers.