Mapping Itinerant Electrons around Kondo Impurities

We investigate single Fe and Co atoms buried below a Cu(100) surface using low temperature scanning tunneling spectroscopy. By mapping the local density of states of the itinerant electrons at the surface, the Kondo resonance near the Fermi energy is analyzed. Probing bulk impurities in this well-defined scattering geometry allows separating the physics of the Kondo system and the measuring process. The line shape of the Kondo signature shows an oscillatory behavior as a function of depth of the impurity as well as a function of lateral distance. The oscillation period along the different directions reveals that the spectral function of the itinerant electrons is anisotropic.Comment: 5 pages, 4 figures, accepted by Physical Review Letter

A first study of the galaxy HRG 2304 and its companion AM 1646-795 (NED01)

Aims. We report the first study of the peculiar ring-like galaxy HRG 2304 (NED02),which was previously classified as a ring galaxy with an elliptical smooth ring. This object was selected to prove that it is a candidate for the Solitaire-type ring galaxies in an early stage of ring formation. The main goal of this work is to provide the spectral characteristics of the current object and its companion AM 1646-795 (NED01). Methods. The study is based on spectroscopic observations in the optical band to highlight the characteristics of this interacting galaxy. To investigate the star formation history of HRG 2304 we used the stellar population synthesis code STARLIGHT. The direct V and B broad band images were used to enhance some fine structures. Results. Along the entire long-slit signal, the spectra of HRG 2304 and its companion resemble that of an early-type galaxy. We estimated a heliocentric systemic redshift of z = 0.0415, corresponding to heliocentric velocities of 12449 km s-1 for HRG 2304 (NED02) and 12430 km s-1 for AM1646-795 (NED01). The spatial variation in the contribution of the stellar population components for both objects are dominated by an old stellar population 2x10^9 < t < 13x10^9 yr. The observed radial-velocity distribution and the fine structures around HRG 2304 suggest an ongoing tidal interaction of both galaxies. Conclusions.The spectroscopic results and the morphological peculiarities of HRG 2304 can be adequately interpreted as an ongoing interaction with the companion galaxy. Both galaxies are early-type, the companion is elliptical, and the smooth distribution of the material around HRG 2304 and its off-center nucleus in the direction of AM1646-795 (NED01) characterize HRG 2304 as a Solitaire-type galaxy candidate in an early stage of ring formation.Comment: Accepted for publication in Astronomy and Astrophysics, 9 pages, 10 figures and 3 table

B811: Field Appraisal of Resource Management Systems Farms Crop Yield and Quality Relationships with Soil Erosion - 1982

This document presents the objectives and third-year results of the Field Appraisal of Resource Management Systems (FARMS) study. The principal objectives of FARMS were to study the relationship of crop yields to predicted soil erosion and to simulate the economics of this relationship. Crop management, soils, conservation practices and management, crop yields, soil chemistry, and sociological data were collected. The data analyzed in preparing this report are from the 800 plots sampled in 1982. This report presents statistics for rill and sheet soil erosion, which is estimated by the Universal Soil Loss Equation (USLE) and assumed to represent a long term rather than short term effect. The report also presents summary statistics for each of the factors in the USLE: for potato yields and quality, for yields of four other field crops, and for soil nutrient analyses.https://digitalcommons.library.umaine.edu/aes_bulletin/1107/thumbnail.jp

B805: Field Appraisal of Resource Management Systems: Crop Yield and Quality Relationships with Soil Erosion—1981

This document presents objectives and results of the Field Appraisal of Resource Management Systems (FARMS) study\u27S second year. The principal objectives of FARMS were to study the relationship of crop yields to soil erosion and to simulate the economic nature of this relationship. Crop management, soils, conservation practices and management, crop yields, soil chemistry, and sociological data were collected from 800 plots in 1981. This report presents statistics for rill and sheet soil erosion, which are estimated by the Universal Soil Loss Equation (USLE) and assumed to represent a long-term rather than short-term effect. The report also presents summary statistics for each of the factors in the USLE: for potato yields and quality, for yields of six other field crops, and for soil nutrient analyses. No general response of potato yield and quality to predicted soil erosion was found. However, individual potato varieties responded differently to predicted soil erosion. Potato yields and specific gravity were found to be significantly related to the Cover and Management factor (C). Potato yield was found to decrease as intensity of potato production increased in the rotation period. Potato yields were significantly reduced when the previous crop was potatoes in comparison to grain or hay.https://digitalcommons.library.umaine.edu/aes_bulletin/1056/thumbnail.jp

Concurrent adaptation to opposing visual displacements during an alternating movement.

It has been suggested that, during tasks in which subjects are exposed to a visual rotation of cursor feedback, alternating bimanual adaptation to opposing rotations is as rapid as unimanual adaptation to a single rotation (Bock et al. in Exp Brain Res 162:513–519, 2005). However, that experiment did not test strict alternation of the limbs but short alternate blocks of trials. We have therefore tested adaptation under alternate left/right hand movement with opposing rotations. It was clear that the left and right hand, within the alternating conditions, learnt to adapt to the opposing displacements at a similar rate suggesting that two adaptive states were formed concurrently. We suggest that the separate limbs are used as contextual cues to switch between the relevant adaptive states. However, we found that during online correction the alternating conditions had a significantly slower rate of adaptation in comparison to the unimanual conditions. Control conditions indicate that the results are not directly due the alternation between limbs or to the constant switching of vision between the two eyes. The negative interference may originate from the requirement to dissociate the visual information of these two alternating displacements to allow online control of the two arms

Theory of real space imaging of Fermi surfaces

A scanning tunneling microscope can be used to visualize in real space Fermi surfaces with buried impurities far below substrates acting as local probes. A theory describing this feature is developed based on the stationary phase approximation. It is demonstrated how a Fermi surface of a material acts as a mirror focusing electrons that scatter at hidden impurities.Comment: 10 pages, 4 figure

Does gravity modelling justify a rifted "Ligurian Basin"?

The geo-historical development of the Ligurian Basin and the structure of the crust and upper mantle in this area are still being discussed. Yet it remains unclear if rifting caused continental break-up and seafloor spreading and one of the key questions is whether rifting can be identified in geophysical measurements. For our investigations we had the following updated data sets at our disposal: the new gravity maps of the AlpArray Gravity Working Group (complete Bouguer - CBA, Free air, and isostatic anomalies) the seismic results of the Lobster campaigns of our GEOMAR partners in the SPP MB4D as well as the dynamic modelling results from our own subproject. The constraining data are supplemented with seismic profile data from French and Italian offshore campaigns, as far as they are usable in publications for us. The GFZ modelling software IGMAS+ was used for an interactive 3D modelling. The resulting model contains density inhomogeneities in the crust as well as in the upper mantle down to a depth of 300 km following the results of dynamic models of our own subproject. Due to the special hybrid modelling of the crust (by polygonal structures) and the upper mantle (by voxels of recent velocity models), the individual contributions to the gravity field are clearly separable. As a further special feature, we point out that the density model used is based on the gravity modelling from the first phase of the SPP MB4D (our former subproject INTEGRATE). Thus, a largely consistent 3D density model for both the Alps and the Ligurian Sea is available for interpretation. The constrained 3D modelling of the gravity field, as well as numerical analyses of the fields (terracing, clustering, filtering, curvature), calculations of the vertical stress and Gravity Potential Energy (GPE) suggest that a rift structure in the area of the Ligurian Sea can be identified and mapped. The interactive modelling is supported by the use of geological maps in the Ligurian Sea area. By overlaying the model gravity maps and the geological maps, the good agreement becomes visible – refer to the attached figure

On the Connection of Anisotropic Conductivity to Tip Induced Space Charge Layers in Scanning Tunneling Spectroscopy of p-doped GaAs

The electronic properties of shallow acceptors in p-doped GaAs{110} are investigated with scanning tunneling microscopy at low temperature. Shallow acceptors are known to exhibit distinct triangular contrasts in STM images for certain bias voltages. Spatially resolved I(V)-spectroscopy is performed to identify their energetic origin and behavior. A crucial parameter - the STM tip's work function - is determined experimentally. The voltage dependent potential configuration and band bending situation is derived. Ways to validate the calculations with the experiment are discussed. Differential conductivity maps reveal that the triangular contrasts are only observed with a depletion layer present under the STM tip. The tunnel process leading to the anisotropic contrasts calls for electrons to tunnel through vacuum gap and a finite region in the semiconductor.Comment: 11 pages, 8 figure

Ordering a rhenium catalyst on Ag(001) through molecule-surface step interaction

In summary, our results present a comprehensive picture of the deposition and self-assembly of thermally stable rhenium com- plexes on the Ag(001) surface. All steps in the molecular growth of fac-Re(bpy)(CO)3Cl on silver rely on the availability of step edges aligned along 〈110〉. Using large-scale DFT calculations the growth hierarchy can be understood and interpreted in terms of the underlying molecular structures and the corresponding binding energies. Rearrangement of the substrate atoms is involved in the molecular cluster growth affecting the local step orientation. This promotes the formation of well-ordered struc- tures. The resulting long-range ordered 1D molecular wires are found to be the prerequisite for 2D growth resulting in long-range ordered molecular monolayers and finally for growing 3D structures. Our results show how well-designed surface mor- phology can be used to guide and control molecular self-assembly in 1D, 2D as well as 3D