S. A. Kovalevskii

Field-emission resonances in STM Intraresonator electron spectroscopy of adsorbates

Abstract A new version of scattering theory is suggested for the 1D electron tunnelling. The Bardeen formula is generalized. The appropriate correction terms form a rapidly converging series. It is shown that the transmission coefficient for an arbitrary 1D barrier can be exactly expressed in terms of the solution to the problem of particle reflection from the barrier sides. The spectral features of the field-emission resonances caused by elastic and inelastic scattering of tunnelling electrons by the 2D lattice of surface atoms and by isolated adsorbed particles are considered. The potentialities of the “intraresonator” vibrational STM spectroscopy of adsorbates are analyzed.

Influence of strong electric fields on the growth, modification, and destruction of thin oxide films at the titanium surface

The influence of strong electric fields (∼107 V/cm) on the growth, modification, and destruction of thin oxide films at the metal surfaces are studied for a titanium tip of a scanning tunneling microscope (STM) oxidized in oxygen at different tip potentials. The spectroscopic measurements show that, in sufficiently strong fields (V≤−7.5 V) preventing migration of oxygen ions from the surface to bulk, the dielectric oxide films can form even for exposures of ∼10 L. At voltages V>−7.5 V, i.e., at lower fields, as well as for the opposite polarity, the conducting oxide films containing predominantly Ti+2 and Ti+3 ions are formed at the tip for the same exposures. The possibility of structural modification in the electric field of STM is demonstrated for titanium nanooxides.

Isotope effect in the vibrational spectra of water measured in experiments with a scanning tunneling microscope

The vibrational frequencies of adsorbed H2O and D2O molecules are measured under high-vacuum conditions by in-cavity scanning tunneling spectroscopy. An isotope effect is observed.

SCANNING TUNNELING VIBRATIONAL SPECTROSCOPY

Abstract A new method for studying of vibronic transitions by scanning tunneling microscope (“nitraresonator electron-vibronic scanning tunneling spectroscopy of adsorbates”) is proposed. Results of experiments carried out by STM “Omicron” where electron-vibronic series of field emission resonances were observed are presented. Frequencies of the resonances correspond to ones of local vibrations of titan oxide and adsorbed hydroxil particles.

Vibrational transitions in experiments with a scanning tunneling microscope

A method of in-cavity scanning tunneling spectroscopy is proposed by which one can observe distinct spectra of electronic-vibrational field-emission resonances.

Multichannel neutralization and reionization in scattering of slow ions

Abstract A simple kinetic model is proposed for the multichannel neutralization of slow ions scattered on a metal surface. The “V” shape peculiarities observed recently in scattering of Ar + , He + , N 2 + , CO + , CO 2 + on Pt(100) are interpreted as classic threshold anomalies arising from crossing of the Fermi level by the ground electron levels of the particles. The model predicts two new types of peculiarities (“h” and “α” types) connected with the competition of multichannel neutralization, reionization and deexcitation. The possibility of spectroscopy of the surface collisional complexes (“spectroscopy of threshold anomalies”) is also pointed out in this report.

Heating of vibrational states of adatoms by the current of a scanning tunneling microscope

Effects associated with the vibrational heating of adatoms by the current of inelastically tunneling electrons were detected in spectroscopic experiments with a scanning tunneling microscope. A relation between the envelope curves of autoemission resonances and the vibrational distribution of particles located under the tip was ascertained.

Threshold peculiarities of the current of low-energy ions scattered on the surface

The low-energy peculiarities at the energy dependences of the current of ions scattered on the surface are analyzed. The peculiarities are determined by the competition of various channels of neutralization and the crossing at small distances of the potential curves of ionic and covalent configurations. The large scale minima at the energy dependences of the current of scattered ions discovered in the experiments of Akazawa and Murata are interpreted as classical threshold features arising as a result of ceasing of neutralization to the ground state. Two new types of peculiarities are predicted: low energy single peaks and small scale combinations of breaks and peaks whose position and halfwidth depend on the parameters of interaction of the excited particles with the surface. The conclusions of a one-dimensional model are confirmed by the results of computer simulation that illustrate some new spectroscopic possibilities of the experiments with the low-energy ion scattering.