In a high-vacuum diode, the volt-ampere characteristic of the thermionic emission of Na+ with surface of NaxAu intermetallide. Its hysteresis was found, which is associated with changes in the surface NaxAu caused by the action of an external electric field. In accordance with the Schottky effect, analysis of the current–voltage characteristic and the value of the work function of the NaxAu surface was estimated. Suggested mechanism of thermionic emission of Na+ from the surface of NaxAu.

Thermal ionization of methenamine (C6H12N4) on the surface of the NaAux intermetallic compound has been studied. It has been established that the processes of decomposition, desorption and ionization of adsorbed compounds, thermally stimulated on the surface, proceed due to the accumulation of energy at the degrees of freedom of the adsorption complex, including the adsorbed compound and a solid, by the mechanism of monomolecular decomposition reactions. In this case, the decomposition of the adsorption complex is accompanied by the desorption of ions that are not in thermal equilibrium with the solid. The uniformity of the temperature dependences of the ion current and their distribution over two groups allowed us to conclude that ions are desorbed from the surface, which correspond to the decays of individual adsorbed molecules, as well as the decays of dimers formed on the surface. The decay of methenamine molecules during thermal ionization occurs in the same way as their decay in vacuum during electron ionization, which indicates the preservation of the bulk structure of methenamine molecules during adsorption and a significant lifetime of the excited state of compounds on NaAux.

A mechanism is proposed for the decomposition of molecular clusters of diethylamine (C2H5)2NН on the surface of the NaAux intermetallic compound with the formation of decomposition products desorbed from the surface, including in the form of ions with m/z from 58 to 197, during heating of the intermetallic compound at a rate of 20 K/s. Exposure of the NaAux surface at a temperature of 320 K in diethylamine vapor leads to the formation of molecular clusters on it. Rapid heating of NaAux at a rate of 20 K/s leads to the decomposition of clusters, desorption, and ionization of the decay products due to the redistribution of internal energy over the degrees of freedom of the cluster. The study of thermal ionization processes during heating of NaAux at a rate of 20 K/s in the temperature range from 600 to 1000 K made it possible to establish that the surface stoichiometry during heating is quasi-stationary, dehydrogenation and ionization of individual diethylamine molecules occur under equilibrium conditions, while for compounds formed in the process of cluster decay, the conditions are not equilibrium

Впервые получены экспериментальные масс-спектры поверхностной ионизации уротропина с поверхности интерметаллида NaAu2. Experimental surface ionization mass spectra of methenamine on the surface of intermetallic NaAu2 were obtained for the first time.

We have studied transient processes of the thermal ionization of sodium on the surface of NaAuy semiconductor film under the action of a variable external electric field. It is established that the kinetics of Na+ ion current during variation of the external field is determined by the establishment of charge distribution in the NaAuy film, while the efficiency of thermal ionization of Na atoms is related to the concentration of holes near the NaAuy/vacuum interface.

AbstractWe have studied transient processes of the thermal ionization of sodium on the surface of NaAu_ y semiconductor film under the action of a variable external electric field. It is established that the kinetics of Na^+ ion current during variation of the external field is determined by the establishment of charge distribution in the NaAu_ y film, while the efficiency of thermal ionization of Na atoms is related to the concentration of holes near the NaAu_ y /vacuum interface.

Simultaneous adsorption of potassium and oxygen on W(100) is studied using the threshold photoemission spectroscopy. A metal potassium film is formed on W(100) in the course of coadsorption of potassium and oxygen at the first stage. At the second stage, the film is transformed into a dielectric layer with the K2O2 stoichiometry.

We have studied threshold processes of Na+ ion emission from a semiconductor NaxAuy film formed on the surface of a gold substrate. In contrast to the classical notions of threshold processes involved in the surface ionization of alkali metal ions from heated metal surfaces, the diffusion exchange of atomic species between the surface and volume of the NaxAuy film ensures stable emission of Na+ ions from the substrate in the region of threshold temperatures. A diffusion mechanism of self-regulation of the surface coverage of alkali metal in the NaxAuy film is proposed.

Исследовано влияние электрического поля на десорбцию ионов натрия из поверхностной полупроводниковой пленки NaAu, сформированной на золотой подложке. Показано, что внешнее электрическое поле оказывает влияние на процессы установления равновесных концентраций катионов натрия в приповерхностной области и на их растворение в объеме пленки сплава NaxAuy.

We investigate how an electric field affects the desorption of sodium ions from the surface of a NaAu semiconductor film formed on a gold substrate. It is shown that an external electric field affects the equilibrium concentrations for sodium cations in the near-surface area and their dilution in a Na x Au y film.

The results of analysis of processes including surface ionization are presented. It is found that these processes do not fit into the classical theory of surface ionization. This concerns the processes with diffusion exchange of particles between the adsorbed layer and the bulk of the emitter, catalytic processes on the emitter surface involving individual centers, as well as processes occurring in the adsorbed layers under illumination, electron bombardment, and in electric fields. We consider the results of analysis of surface ionization of alkali metal atoms and organic molecules on the surface of gold intermetallide (Na (x) Au (y) ), considerably extending information about this phenomenon.

The formation of Na+ and Cs+ ions on and their thermal desorption from the surface of a NaAu alloy film grown on metallic gold are studied. It is shown that thermionic emission from insulator-coated metallic substrates is governed by a sequence of processes, such as diffusion of Na and Cs adatoms into the film, ionization of these atoms at the insulator-metal interface, diffusion of the resulting ions toward the surface, and desorption of the ions. The effect of weak electric fields on ion diffusion and desorption is investigated.

A method for controlling the yield of ionized products from a heterogeneous reaction of amines on the surface of an Na x Au y alloy is proposed, which is based on the effect of a weak electric field on the diffusion of Na + ions.

A heated Na/Au surface alloy film grown on gold substrate is found to be an efficient thermal desorber of polyatomic positive ions produced from organic molecules and oxygen falling on its surface. The ionization of diethylamine molecules at this thermal emitter is studied by mass-spectrometry means. Special features of the heterogeneous formation of polyatomic complexes and the thermal desorption of cluster ions are revealed. A model explaining the efficient thermal desorption of ions from the surface of an alloy which is a wide-gap semiconductor is proposed.

The initial stage of formation of ultrathin potassium films on W(100) is studied by threshold photoemission spectroscopy using p-and s-polarized light in a photon energy range of 1.6–3.5 eV. It is found that the photoemission current spectrum depends on the surface coverage by the alkaline atoms. Mathematically, this shows up as the dependence of the matrix elements responsible for photoemission excitation on surface coverage. The matrix elements vary because the photoelectron escape depth is small; hence, the emission comes from the surface layer under irradiation by both p-and s-polarized light.

Threshold photoemission spectroscopy is used to study adsorption of Cs atoms on an Au substrate. It is found that. at initial stages of Cs deposition the photoelectron current induced by p- as well as by s-polarized light is caused exclusively by excitation of the upper layer of the surface. Photoelectronic properties of the Cs/Au system are connected with the formation at a submonolayer Cs coverage of a band of induced surface states with binding energy close to the Fermi level. Analysis of the photoemission matrix elements dependence on the Cs coverage reveals a possibility of finding the dependence of the surface states density on the adsorbate concentration, as well as the detection of the onset of the CsAu surface alloy phase formation.