The ability of a scanning tunneling microscope to manipulate single atoms is used to build well-defined gold chains on NiAl(110). The electronic properties of the one-dimensional chains are dominated by an unoccupied electron band, gradually developing from a single atomic orbital present in a gold atom. Spatially resolved conductance measurements along a 20-atom chain provide the dispersion relation, effective mass, and density of states of the free electron-like band. These experiments demonstrate a strategy for probing the interrelation between geometric structure, elemental composition, and electronic properties in metallic nanostructures.

A scanning microwave microscope (SMM) for spatially resolved capacitance measurements in the attofarad-to-femtofarad regime is presented. The system is based on the combination of an atomic force microscope (AFM) and a performance network analyzer (PNA). For the determination of absolute capacitance values from PNA reflection amplitudes, a calibration sample of conductive gold pads of various sizes on a SiO(2) staircase structure was used. The thickness of the dielectric SiO(2) staircase ranged from 10 to 200 nm. The quantitative capacitance values determined from the PNA reflection amplitude were compared to control measurements using an external capacitance bridge. Depending on the area of the gold top electrode and the SiO(2) step height, the corresponding capacitance values, as measured with the SMM, ranged from 0.1 to 22 fF at a noise level of ~2 aF and a relative accuracy of 20%. The sample capacitance could be modeled to a good degree as idealized parallel plates with the SiO(2) dielectric sandwiched in between. The cantilever/sample stray capacitance was measured by lifting the tip away from the surface. By bringing the AFM tip into direct contact with the SiO(2) staircase structure, the electrical footprint of the tip was determined, resulting in an effective tip radius of ~60 nm and a tip-sample capacitance of ~20 aF at the smallest dielectric thickness.

Electronic properties of single Pd atoms, deposited on Al(2)O(3)/NiAl(110), have been characterized by scanning tunneling spectroscopy at 12 K. The spectra reveal distinct conductivity resonances, assigned to discrete electronic levels in the atom. The energy position of the resonances reflects adsorption properties of Pd atoms on different sites of the oxide support. Mapping the spatial extent of conductivity channels in the Pd atoms yields the symmetry of the underlying electronic states. The results demonstrate the effect of a heterogeneous oxide surface on the electronic structure of adsorbed metal atoms.

The original intent in Fig. 4(b) was to show the k 2 dependence of the energy states of an electron in an artificial gold atomic chain, realizing the one-dimensional particle in a finite box, where k n=L, n 1; 2; 3; . . . , and L is the length of the chain. The duplication of the data points on the negative k axis in Fig. 4(b) is misleading even though it shows visually the complete parabola. The correct way to present the results is to plot only positive k values. The corrected version of Fig. 4(b) for an 11-atom gold chain is reprinted below as Fig. 1 where energy is plotted versus k 2 . This change in Fig. 4(b) does not affect other parts of our Letter, which remain the same. To reinforce the k 2 energy dependence, results for a 20-atom gold chain [1] are also shown below as Fig. 2.

The scanning microwave microscope is used for calibrated capacitance spectroscopy and spatially resolved dopant profiling measurements. It consists of an atomic force microscope combined with a vector network analyzer operating between 1–20 GHz. On silicon semiconductor calibration samples with doping concentrations ranging from 1015 to 1020 atoms/cm3, calibrated capacitance-voltage curves as well as derivative dC/dV curves were acquired. The change of the capacitance and the dC/dV signal is directly related to the dopant concentration allowing for quantitative dopant profiling. The method was tested on various samples with known dopant concentration and the resolution of dopant profiling determined to 20% while the absolute accuracy is within an order of magnitude. Using a modeling approach the dopant profiling calibration curves were analyzed with respect to varying tip diameter and oxide thickness allowing for improvements of the calibration accuracy. Bipolar samples were investigated and nano-scale defect structures and p-n junction interfaces imaged showing potential applications for the study of semiconductor device performance and failure analysis.

The importance of substrate-mediated adsorbate-adsorbate interactions on electronic states has been demonstrated for Au dimers on NiAl(110) with a scanning tunneling microscope and density functional calculations. An unoccupied resonance observed in single Au atoms splits into a doublet in Au dimers. The energy splitting depends inversely on the distance between the two adatoms, revealing the relative importance of direct and substrate-mediated interactions. Spatially resolved conductance measurements of Au dimers reveal the symmetric and antisymmetric characters of the doublet states.

A method is presented for determining the magnetomechanical ratio g′ in a thin ferromagnetic film deposited on a microcantilever via measurement of the Einstein–de Haas effect. An alternating magnetic field applied in the plane of the cantilever and perpendicular to its length induces bending oscillations of the cantilever that are measured with a fiber optic interferometer. Measurement of g′ provides complementary information about the g factor in ferromagnetic films that is not directly available from other characterization techniques. For a 50nm Ni80Fe20 film deposited on a silicon nitride cantilever, g′ is measured to be 1.83±0.10.

Comparison of S 11 and S 11As noted in the manuscript we preferably use the S 11 = dS 11 dV data channel as opposed to the raw S 11 signal, primarily due to the robustness of S 11 (as all values here are complex unless otherwise noted, the tilde has been dropped). Shown in Figure S1 is a comparison of these data channels. Figure S1(a-b) shows the raw and unprocessed S 11 data, corresponding to the V b = 0 V image in Figure 2 (real and imaginary components are calculated from the amplitude and phase channels acquired). The S 11 signal remains stable, showing little drift in either signal or noise. In contrast, the simultaneously acquired unprocessed S 11 channels (c,d) show significant drift in both amplitude