F. I. Dalidchik

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.

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.

On the observation of a single paramagnetic center in experiments with a scanning tunneling microscope

It is shown that exchange splitting is observed in the field emission resonance spectrum when a paramagnetic center is present in the contact of a scanning tunneling microscope. The effect makes it possible to detect single electron spins.

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.

Reconstruction of heterogeneous single-channel neutralization kinetics by the method of fast-ion grazing scattering from metal surfaces

A method is suggested for the unambiguous reconstruction of the heterogeneous slow-ion neutralization kinetics near the surface of a conductor. The method is based on the special features of fast ion grazing scattering with above-thermal energies of translational motion along the normal. It is shown that the angular distributions of fast particles reflected from the surface are related to the slow-ion neutralization rate by a simple algebraic expression. The method allows the reconstruction of the coordinate dependence for the neutralization rate and the interaction potentials. Its possibilities are demonstrated by the example of neutralizing fast He+ ions (ion energies E1≈2 keV and glancing angles θ0≈0.5°–0.8°) scattered from the A1(111) surface.

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.