Scanning tunneling spectroscopy

About: Scanning tunneling spectroscopy is a research topic. Over the lifetime, 7886 publications have been published within this topic receiving 213828 citations.

Direct observation of Friedel oscillations around incorporated SiGa dopants in GaAs by low-temperature scanning tunneling microscopy.

Abstract: We report the direct imaging of electrically active Si dopants near the GaAs(110) surface with a scanning tunneling microscope at a temperature of 4.2 K. In the filled state images, we observe patterns of rings which are centered around the individual doping atoms. We believe these ring patterns are induced by the individual impurities, which, due to their charge, disturb the local potential and cause oscillations in the charge density, also called Friedel oscillations. In the empty state images no Friedel oscillations can be observed.

Mechanisms of Molecular Manipulation with the Scanning Tunneling Microscope at Room Temperature: Chlorobenzene/Si(111)-(7×7)

Abstract: We report a systematic experimental investigation of the mechanism of desorption of chlorobenzene molecules from the $\mathrm{S}\mathrm{i}(111)\ensuremath{-}(7\ifmmode\times\else\texttimes\fi{}7)$ surface induced by the STM at room temperature. We measure the desorption probability as a function of both tunneling current and a wide range of sample bias voltages between $\ensuremath{-}3\text{ }\mathrm{V}$ and $+4\text{ }\mathrm{V}$. The results exclude field desorption, thermally induced desorption, and mechanical tip-surface effects. They indicate that desorption is driven by the population of negative (or positive) ion resonances of the chemisorbed molecule by the tunneling electrons (or holes). Density functional calculations suggest that these resonant states are associated with the $\ensuremath{\pi}$ orbitals of the benzene ring.

Tunneling currents in electron transfer reaction in proteins. II. Calculation of electronic superexchange matrix element and tunneling currents using nonorthogonal basis sets

Abstract: In this paper we further develop the concept of interatomic tunneling currents [A.A. Stuchebrukhov, J. Chem. Phys. 104, 8424 (1996)] for the description of long‐range electron tunneling in proteins. Here we discuss a formulation of the theory for the case when nonorthogonality of the atomic basis set of the medium propagating electron is explicitly taken into account. This method provides an effective computational scheme for an exact, i.e., nonperturbative, evaluation (in one‐electron approximation) of the superexchange electron tunneling matrix element, and allows one to determine which regions in the protein matrix are important for the tunneling process. The theory is applied for calculation of tunneling currents and the electronic matrix element in His126‐Ru‐modified blue copper protein azurin from a recent experimental work of Gray and co‐workers. Analysis of interatomic currents reveals a nontrivial structure of the tunneling flow between donor and acceptor in the intervening protein medium in this system.

Band Gap Modulated by Electronic Superlattice in Blue Phosphorene.

Abstract: Exploring stable two-dimensional materials with appropriate band gaps and high carrier mobility is highly desirable due to the potential applications in optoelectronic devices. Here, the electronic structures of phosphorene on a Au(111) substrate are investigated by scanning tunneling spectroscopy, angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT) calculations. The substrate-induced phosphorene superstructure gives a superlattice potential, leading to a strong band folding effect of the sp band of Au(111) on the band structure. The band gap could be clearly identified in the ARPES results after examining the folded sp band. The value of the energy gap (∼1.1 eV) and the high charge carrier mobility comparable to that of black phosphorus, which is engineered by the tensile strain, are revealed by the combination of ARPES results and DFT calculations. Furthermore, the phosphorene layer on the Au(111) surface displays high surface inertness, leading to the absence of multi...