V. I. Troyan

The size dependence of thermal EMF for Au, Pd, and Pt nanoclusters deposited onto highly oriented pyrolitic graphite surface

Data are presented on the tunnel current-voltage characteristics of gold, palladium, and platinum nanoclusters formed by pulsed laser deposition on the surface of highly oriented pyrolytic graphite. Differential tunnel current-voltage characteristics measured by scanning tunnel spectroscopy have been used to restore the size dependences of the thermal emf values of the studied nanoclusters. The behavior of the thermal emf of the nanoclusters as depending on their sizes has been found to depend on the nature of a metal. The data obtained have been analyzed.

Roughening of a Si(100) surface induced by the adsorption of oxygen near the solid-oxide nucleation threshold

An investigation of the processes on a Si(100) surface interacting with oxygen near the solid-oxide nucleation threshold using x-ray photoelectron spectroscopy and atomic-force microscopy is described. The nucleation threshold is the boundary between the temperature and oxygen pressure regions where a phase transition with the formation of a submonolayer oxide and a roughening transition caused by oxygen adsorption occur. Near the nucleation threshold, either a random rough relief or a quasiperiodic structure is formed on a surface coated with chemisorbed oxygen. The formation of the rough relief due to oxygen adsorption has been interpreted within the theory of phase transitions as a result of vacancy clustering. A model that allows one to describe the dynamics of processes on the surface near the nucleation threshold in qualitative and in some cases in quantitative terms has been suggested.

Mass selective laser cooling of 229Th3+ in a multisectional linear Paul trap loaded with a mixture of thorium isotopes:

We consider an experiment on trapping and laser cooling of 229Th3+ ions in a linear Paul trap in the presence of undesirable impurities such as ions of the radioactive isotope 228Th3+. We suggest a method of separating these impurities by means of selective laser cooling utilizing the isotope shift of cooling transitions in 229Th3+ and 228Th3+ ions. According to our estimation, the isotope shift is equal to 3.4u2009GHZ and makes laser separation of these isotopes possible.

On determination of the fluctuation sensitivity limit of the induction method for the measurement of surface roughness

The fluctuation sensitivity limit of the induction method for the measurement of surface roughness has been determined. It has been shown that, for a profilograph used in this work, the minimum value of magnetic induction resulting from current thermal fluctuations is equal to 3 × 10−7 G. According to the experimental data, a change in the surface relief height by 2 nm varies the magnetic induction by 2 × 10−6 G, i.e., by a value exceeding the value determined for the thermal fluctuations by an order of magnitude. Hence, the design of the differential inductive sensor proposed for the profilograph can be used to measure the surface roughness on the order of several fractions of a nanometer.

Formation of local thorium silicate compound by electrochemical deposition from an acetone solution of thorium nitrate

The results of the study of local formation (diameter of deposited area is about 100u2009μm) of thorium oxide coatings on SiO2/Si(001) surface by electrochemical deposition are presented. It was found that the electrochemical deposition of thorium atoms from an acetone solution of Th(NO3)4 on silicon surface lead to the formation of thorium-based films. The results of surface analysis by local X-ray photoelectron spectroscopy and X-ray photoemission indicate that these films contain of thorium-, silicon-, oxygen- and carbon-based compounds. After 30u2009h of annealing at 1350u2009°C in atmosphere carbon pulled completely, and the compound transforms into thorium silicate films ThSiO4 (Huttonite). Our primary study of ThSiO4 compound by reflection electron energy loss spectroscopy showed that this system have energy gap ~7.7u2009eV and can be useful for further research of «nuclear clocks» as well as for «nuclear battery».Graphical Abstract

Method of the production and trapping of thorium ions for nuclear transition investigation

This paper describes the techniques of production and trapping of thorium ions required to perform spectroscopic studies of thorium nuclear transition.

Loading of mass spectrometry ion trap with Th ions by laser ablation for nuclear frequency standard application

We describe an original multisectional quadrupole ion trap aimed to realize nuclear frequency standard based on the unique isomer transition in thorium nucleus. It is shown that the system effectively operates on Th+, Th2+ and Th3+ ions produced by laser ablation of metallic thorium-232 target. Laser intensity used for ablation is about 6u2009GW/cm2. Via applying a bias potential to every control voltage including the RF one, we are able not only to manipulate ions within the energy range as wide as 1–500u2009eV but to specially adjust trap potentials in order to work mainly with ions that belong to energy distribution maximum and therefore to effectively enhance the number of trapped ions. Measurement of energy distributions of 232Th+, 232Th2+, 232Th3+ ions obtained by laser ablation allows us to define optimal potential values for trapping process. Observed number of ions inside trap in dependence on trapping time is found to obey an unusually slow – logarithmic decay law that needs more careful study.