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.

Single-molecule reaction and characterization by vibrational excitation.

Abstract: Controlled chemical reaction of single trans-2-butene molecules on the Pd(110) surface was realized by dosing tunneling electrons from the tip of a scanning tunneling microscope at 4.7 K. The reaction product was identified as a 1,3-butadiene molecule by inelastic electron tunneling spectroscopy. Threshold voltage for the reaction is $\ensuremath{\sim}365\text{ }\mathrm{m}\mathrm{V}$, which coincides with the vibrational excitation of the C-H stretching mode. The reaction was ascertained to be caused by C-H bond dissociation by multiple vibrational excitations of the C-H stretching mode via inelastic electron tunneling process.

The physical and chemical properties of ultrathin oxide films.

Abstract: Thin oxide films (from one to tens of monolayers) of SiO2, MgO, NiO, Al2O3, FexOy, and TiO2 supported on refractory metal substrates have been prepared by depositing the oxide metal precursor in a background of oxygen (ca 1 x 10(-5) Torr). The thinness of these oxide samples facilitates investigation by an array of surface techniques, many of which are precluded when applied to the corresponding bulk oxide. Layered and mixed binary oxides have been prepared by sequential synthesis of dissimilar oxide layers or co-deposition of two different oxides. Recent work has shown that the underlying oxide substrate can markedly influence the electronic and chemical properties of the overlayer oxide. The structural, electronic, and chemical properties of these ultrathin oxide films have been probed using Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (ELS), ion-scattering spectroscopy (ISS), high-resolution electron energy loss spectroscopy (HREELS), infrared reflectance absorption spectroscopy (IRAS), temperature-programmed desorption (TPD), scanning tunneling microscopy (STM), and scanning tunneling spectroscopy (STS).

Spin-Polarized Vacuum Tunneling into the Exchange-Split Surface State of Gd(0001)

Abstract: Spin-polarized tunneling is demonstrated on Gd(0001) thin films using ferromagnetic probe tips in a low-temperature scanning tunneling microscope. The magnetic field dependent asymmetries in the differential tunneling conductivity are found at bias voltages which correspond to the energies of the spin components of the exchange-split Gd(0001) surface state. Maps of the spatial variation of the asymmetry reveal the magnetic structure of Gd(0001) thin films with a lateral resolution better than 20 nm. It is found that magnetic tip coatings thicker than 100 monolayers Fe may modify the sample domain structure due to the stray field of the tip.

Spin-polarized scanning tunneling microscopy with antiferromagnetic probe tips.

Abstract: We have performed low temperature spin-polarized scanning tunneling microscopy (SP-STM) of two monolayers Fe on W(110) using tungsten tips coated with different magnetic materials. We observe stripe domains with a magnetic period of 50 +/- 5 nm. Employing Cr as a coating material we recorded SP-STM images with an antiferromagnetic probe tip. The advantage of its vanishing dipole field is most apparent in external magnetic fields. This new approach resolves the problem of the disturbing influence of a ferromagnetic tip in the investigation of soft magnetic materials and superparamagnetic particles.

Geometric and electronic structure of antimony on the GaAs(110) surface studied by scanning tunneling microscopy

Abstract: Antimony overlayers on the GaAs(110) surface have been studied by scanning tunneling microscopy and spectroscopy. The Sb is observed to grow as a 1\ifmmode\times\else\texttimes\fi{}1 ordered monolayer. The positions of the Sb atoms in the surface unit cell are deduced from voltage-dependent imaging, and compared with previously proposed structural models. A best fit is found for a model in which the Sb atoms occupy positions similar to what would be the positions of Ga and As atoms at an unrelaxed GaAs(110) surface, in agreement with the results from low-energy electron-diffraction experiments. The surface-state density is measured with tunneling spectroscopy. Two filled-state peaks and one empty-state peak are observed in the spectra, as well as a band-gap region with a width nearly equal to the bulk band gap. These observations are compared with previous photoemission results and theoretical calculations.