Interaction Of Slow Electrons Research Articles

Interaction of Slow Electrons with Thermally Evaporated Manganese(II) Acetylacetonate Complexes.

Complexes of metal acetylacetonate are used as general precursors for the synthesis of metal oxide nanomaterials. In the present work, we study the interaction of low-energy (<10 eV) electrons, produced abundantly as secondary electrons during the bombardment of the substrate by the primary particles, with thermally evaporated manganese(II) acetylacetonate complexes. We found that the acetylacetonate anion ([acac]-) is the major anionic species produced, while the second most abundant is the parent anion [Mn(II)(acac)2]-. This observation differs from those reported from electron attachment to Cu(acac)2, for which [Cu(II)(acac)2]- is the predominant anion [Kopyra et al. Phys. Chem. Chem. Phys. 2018, 20, 7746]. The experimental data are supported by theory to provide information on the physical-chemistry processes initiated by slow electrons to the organometallic precursor and to interpret the different behavior of Mn(acac)2 compared to Cu(acac)2.

Scattering of slow electrons by inert gas atoms. Effective polarization potential method

The problem of selecting the polarization-correlation potential Vpol for describing the interaction of electrons with atomic targets is examined. Based on the differential cross section for electron scattering by the hydrogen atom calculated using the partial wave method and the exact exchange operator, the optimal form of this potential is determined. It is demonstrated that the parameters of the potential Vpol can be determined from the condition of equality of the calculated and experimental values of the electron affinity of the hydrogen atom. For the interaction of slow electrons with inert gas atoms, the polarization parameter Rp is proposed to be determined from the known position of the Ramsauer minimum in the total elastic scattering cross section. In particular, calculations are performed for krypton and argon atoms. The results agree well with numerous experimental and theoretical published data.

Interaction of slow electrons with methyl phosphate esters

We report computed cross sections for low-energy elastic collisions of electrons with the methyl esters of phosphoric acid, monomethyl, dimethyl, and trimethyl phosphate, and with phosphoric acid itself. For phosporic acid and monomethyl phosphate, polarization effects are included in the calculation, while the two larger molecules are treated in the static-exchange approximation, that is, with polarization neglected. The integral elastic cross sections exhibit broad shape resonances above 5eV that give rise to strong variations in the differential cross section with energy. However, no shape resonances are evident below 5eV. We compare our results to previous calculations and measurements and discuss their relevance to electron-induced damage to the DNA backbone.

Interaction of slow electrons with surface: Empty electronic states and inelastic scattering effects

The fine structure of experimental true secondary-electron emission spectra along the normal to a clean W(1 1 0) surface, target (or total) current spectra, and low-energy-electron-transmission spectra along the normal to a clean 2 H-MoS 2(0 0 0 1) surface are interpreted theoretically. It is shown that the fine structure of these spectra is mainly due to the electronic structure of unoccupied high-level electronic states (above the vacuum level), which become occupied by electrons entering the solid. In addition, a comparison to existing theoretical and experimental data is given.

Interaction of Laser Light and Electrons with Nanotubes

Electronic states in designed geometries are attracting considerable attention. In this work, it is shown that it may be possible to induce ultrafast mechanical rotation in nanotubes using circularly polarized light. We predict a novel set of Rydberg-like electronic states around nanotubes having long lifetimes and exotic properties. Preliminary work on the interaction of slow electrons with an array of parallel nanotubes is discussed.

Multimode combined intense laser-induced electron acceleration and violent bunch compression

The ponderomotive potential structure of a multimode combined intense laser beam is studied. Using a three-dimensional test particle simulation, the interaction of slow electrons with the combined laser beam in vacuum is investigated. The calculation shows that electrons distributed on a large scale can be accelerated to relativistic energy in vacuum. A violent longitudinal bunch compression phenomenon is also presented and discussed.

Interaction of slow electrons with Langmuir-Blodgett films studied by high resolution electron energy loss spectroscopy

Vibrational and complete high resolution spectra (HREELS) of Langmuir-Blodgett (LB) monolayers of mixtures of pure hydrogenated and deuterated stearic acids on aluminum substrates were recorded. The results show that electrons penetrate into the film and relax in the conduction band of the insulating film. Complete spectra are mainly composed of different regions corresponding to vibrational losses, and to exponential decay of the intensity of backscattered electrons where superimposed structures, fixed to the vacuum level, are observed for primary energies higher than 4 eV. An emission of thermalized electrons is also observed near the vacuum level. Conclusions about the different aspects of this interaction are inferred combining information obtained from the different regions in the spectra.

Interaction of slow electrons with organic films: theoretical and experimental HREELS studies on selectively deuterated molecules

The scattering processes of slow electrons in high-resolution electron-energy-loss spectroscopy (HREELS) at the surface of organic solids have been studied, both theoretically and experimentally. We used selectively deuterated molecules which were prepared in highly ordered films by the Langmuir-Blodgett (LB) technique. In the framework of a microscopic approach the intensity ratios for CD- and CH-stretching vibrations in the dipolar and impact limit were estimated. The broad angular distribution of elastically reflected electrons scattered at organic surfaces as well as the anisotropy of the films were taken into account. In a first set of experiments the influence of the substitution of hydrogen by deuterium on the intensity of the corresponding methyl and methylene stretching vibrations was measured. Comparison of the results with the theoretical considerations supports a dipolar-dominated scattering at around 5 eV with an increase of the impact contribution at lower energies. Second, the information depth and its dependence on the impact energy of the electrons was studied. The strong increase in the information depth towards lower electron energies can be correlated with a decrease of the dipolar scattering intensity and an enhancement of short-range interaction.

Interaction of slow electrons with density fluctuations in condensed materials: Calculation of stopping power.

The calculation of the energy-resolved scattering of slow (\ensuremath{\lesssim}3 eV) electrons from density fluctuations is extended from crystalline semiconductors to amorphous, condensed materials (solid or liquid). In the Born approximation, the scattering is proportional to S(q,\ensuremath{\omega}), the ``dynamical structure factor'' of the material. This factor, which exhibits some basic similarities and differences between solids and liquids, is determined by hydrodynamical parameters in the low-q range relevant to slow electrons. For solids, the scattering law remains unchanged when extended from crystalline to amorphous states, so the stopping power remains unchanged also. The scattering law changes when extended to liquids, but the calculated stopping power remains effectively unchanged.

Interaction of slow electrons with atoms and molecules in solid films

Interaction of slow electrons with atoms and molecules in solid films

Short- and long-range interactions of slow electrons in condensed matter: Effects on reflection and transmission.

The Coulomb interaction of an electron with each electron or nucleus in its environment is Fourier analyzed into components with wave vectors q. These components are classified as long (short) range when q is smaller (larger) than the electron's wave number p. The contrasting characteristics of each class are discussed. Electron reflection at a material's surface measures the effect of short-range components only.

Local approximations of exchange interaction in electron-molecule collisions: the methane molecule

The interaction of slow electrons (collision energies up to about 20 eV) with polyatomic targets is examined for the specific case of the methane molecule in order to study the effect on total cross sections of various local approximations for the exchange interaction between bound and continuum electrons. It is found that the tail of such an interaction, outside the 'hard-core' region of the static potential, plays an important role at very low collision energies and ultimately controls the correct appearance of the experimentally found Ramsauer-Townsend (RT) minimum in the integral elastic cross section. Very good agreement between computed and measured values for the cross sections is found when using the modified semiclassical exchange approximation (MSCE) proposed. The broad resonance, which appears at experimental energies of around 8 eV, is also satisfactorily reproduced by the present methods.

On the role of background scattering in the resonance interaction of slow electrons with molecules

The problem of interaction of slow electrons e- with molecules XY has been formulated directly for the collision T operator. A basis of continuous spectrum states has been used in which the K matrix, related to the collision operator, is additive with respect to the direct and the resonance interaction mechanism. This makes it possible to perform an analytical study on the contribution of these mechanisms to the processes of scattering and dissociative attachment (DA) of electrons as well as to define the validity of the theoretical approaches available. It has been shown that the elastic background scattering decreases the DA rate in the low-energy case and can be taken into account by a redefinition of the effective non-local optical potential which is introduced in the configuration interaction method to describe nuclear motion in intermediate states of XY-. The inelastic background scattering distorts the form of the resonance peaks and increases the DA rate due to the appearance of new reaction channels taking place when the molecule undergoes vibrational excitation in the collision.

The semiclassical approximation in the local theory of resonance inelastic interaction of slow electrons with molecules

The semiclassical approach is developed to calculate the cross sections of vibrational excitation and dissociative attachment for diatomic molecules within the framework of the 'boomerang model'. The cross sections are shown to factorise in this approximation. This feature results from the fact that processes proceed via two stages-capture of the incident electron into an intermediate state and the decay of this state. The formulae obtained reveal the energy dependence of the cross sections on the parameters of the system. Numerical calculations for N2, CO, H2, HD and D2 confirm the high accuracy of the method.

Excited electron orbit collapse and atomic spectra

The reasons for the two-well potential in free atoms and the collapse of the orbit (or wave function) of an electron are discussed. Theoretical data on the dependence of the collapse on the atomic number, the degree of ionization, the configuration, the many-electron quantum numbers, etc., are put in systematic form. A similar effect occurs for a free electron moving in an atomic field. Various manifestations of the collapse and the potential barrier in the energy spectra are discussed: an anomalous behavior of the quantum defect, a nonmonotonic variation in the type of binding in an isoelectronic series, a broadening of the energy spectrum, and a pronounced mixing of configurations. Effects of the collapse and the barrier in photoabsorption spectra are also discussed: a suppression of the Rydberg series, a shift of the absorption edge, the appearance of giant absorption resonances corresponding to transitions in the discrete spectrum, and the alignment of ions during photoionization of atoms. Experimental data which furnish evidence that the interaction of slow electrons with atoms is quasiresonant in the case of a two-well potential are reviewed briefly.

Radiative interaction of slow electrons with metal surfaces

Abstract Metals are traditionally referred to as nonluminescent substances. There appear, however, an ever-increasing number of publications dealing with the luminescence of metals in the visible and near uv region when irradiated with slow electrons (of about 100 eV energy). The characteristics of the luminescence turned out to be very sensitive to conditions of the surface. This paper represents a short review of experimental research in the field of, and theoretical models for, the radiative interaction of slow electrons with metal surfaces. It is emphasized that this phenomenon can be used for studying the electron properties of metal surfaces and the adsorption and desorption processes on them.

Interaction of slow electrons with surfaces: II. Evaporated gold and silver layers on {100} vanadium

Abstract Total current spectroscopy (TCS) has been used to study the growth of gold and silver on {100} vanadium surfaces. A slow transition from TCS curves characteristic of vanadium to curves characteristic of the noble metals is observed, accompanied by an increase in the net work function-more rapid for silver than for gold. Vanadium characteristics are lost from the TCS curves for mean overlayer thicknesses ≳ 15 A, and a simple analysis shows that the thickness of the surface zone from which TCS signals originate is approximately given by the electron mean free path. Observations of progressive attenuation of a characteristic vanadium feature with increasing mean thickness of overlayer permits separation into stages of nucleation and growth. There is a critical nucleus size of ≃ 2 A for silver and ≃ 4 A for gold.

Interaction of slow electrons with surfaces: I. Desorption and absorption of gas on {100} vanadium

Abstract Total current spectroscopy (TCS) has been used to probe the {100} surface of a single crystal of vanadium. Primary electron energies were in the range 0–10 eV. Surface potential measurements are described for desorption of residual gas between room temperature and 1500°C. A value for the work function of vanadium is obtained from comparative measurements using evaporated layers of silver. Structure in the TCS curves is a consequence of both the reflection properties of the vanadium surface and excitation of interband transitions in the solid. Additional structure which appears after adsorption is due to resonances in the adsorbed layer. A method is described for the extraction of this component from the spectra and a simple analysis given in terms of multiple electron scattering. In this way estimates of the layer thickness d and the average potential V can be made.

1197. Interaction of slow electrons with adsorbed organic molecules: O M Artamonov and V I Zyn, Uch Zap LGU, No 354, 1970, 86–91 ( in Russian)

1197. Interaction of slow electrons with adsorbed organic molecules: O M Artamonov and V I Zyn, Uch Zap LGU, No 354, 1970, 86–91 ( in Russian)

Interaction of slow electrons with oxygen adsorbed on the (110) face of silicon: M I Datsiev et al, Uch Zap LGU, No 354, 1970, 58–68 ( in Russian)

Interaction of slow electrons with oxygen adsorbed on the (110) face of silicon: M I Datsiev et al, Uch Zap LGU, No 354, 1970, 58–68 ( in Russian)