MoS2(1-x) Se2x single-layer films are prepared using a mixture of organic selenium and sulfur precursors as well as a solid molybdenum source. The direct bandgaps are found to scale nearly linearly with composition in the range of 1.87 eV (pure single-layer MoS2 ) to 1.55 eV (pure single-layer MoSe2 ) permitting straightforward bandgap engineering.

The high intrinsic spin and long spin relaxation time of manganese-12-acetate (Mn(12)) makes it an archetypical single molecular magnet. While these characteristics have been measured on bulk samples, questions remain whether the magnetic properties replicate themselves in surface supported isolated molecules, a prerequisite for any application. Here we demonstrate that electrospray ion beam deposition facilitates grafting of intact Mn(12) molecules on metal as well as ultrathin insulating surfaces enabling submolecular resolution imaging by scanning tunneling microscopy. Using scanning tunneling spectroscopy we detect spin excitations from the magnetic ground state of the molecule at an ultrathin boron nitride decoupling layer. Our results are supported by density functional theory based calculations and establish that individual Mn(12) molecules retain their intrinsic spin on a well chosen solid support.

We present a novel way of performing kinetic Monte Carlo simulations which does not require an a priori list of diffusion processes and their associated energetics and reaction rates. Rather, at any time during the simulation, energetics for all possible (single or multi-atom) processes, within a specific interaction range, are either computed accurately using a saddle point search procedure, or retrieved from a database in which previously encountered processes are stored. This self-learning procedure enhances the speed of the simulations along with a substantial gain in reliability because of the inclusion of many-particle processes. Accompanying results from the application of the method to the case of two-dimensional Cu adatom-cluster diffusion and coalescence on Cu (111) with detailed statistics of involved atomistic processes and contributing diffusion coefficients attest to the suitability of the method for the purpose.

Growth shapes of Ag islands formed on Ag͑111͒ during submonolayer deposition at different temperatures were studied with scanning tunneling microscopy, and analyzed via kinetic Monte Carlo simulation of a suitable atomistic lattice-gas model. Distinct shape transitions can be observed, from dendrites with triangular envelopes at low temperatures ͑below 140 K͒ to more isotropic fat fractal islands at intermediate temperatures, and then to distorted hexagonal shapes with longer B steps and shorter A steps at higher temperatures ͑above 170 K͒. In contrast, the equilibrium island shapes in this system are almost perfect hexagons displaying a near-sixfold symmetry. Modeling reveals that the broken symmetry of growth shapes at low and high temperatures derives from the interplay of diffusion-mediated aggregation with different aspects of a corner diffusion anisotropy. The broken symmetry is less clear at intermediate temperatures, where the near-isotropic fractal shapes reflect in part a kink Ehrlich-Schwoebel effect.

We have carried out scalar relativistic density functional theory calculations within the projector augmented wave scheme and the pseudopotential approach, to examine the effect of ligands on the geometric and electronic structure of four Au 13 isomers: planar, flake, cuboctahedral, and icosahedral clusters. We find, in agreement with previous theoretical calculations, that for the clean cluster the planar geometry has the lowest total energy while the icosahedral and cuboctahedral structures undergo Jahn-Teller distortion. On the other hand, when ligated by phosphines, the icosahedron is found to assume the lowest total energy. The rationale for the stabilization of the icosahedron in the ligated Au 13 cluster is traced to the ligand-induced charge transfer from the surface Au-Au to Au-ligand bonds leading to the formation of a strong Au-ligand covalent bond and introduction of a compressive strain which further weakens the Au-Au bonds.