Transmission Of Low-energy Electrons Research Articles

Stable transmission of low energy electrons in glass tube with outer surface grounded conductively shielding

<sec>The electron microbeam is useful for modifying certain fragments of biomolecule. It is successful to apply the guiding effect to making the microbeam of positively charged particles by using single glass capillary. However, the mechanism for the electron transport through insulating capillaries is unclear. Meanwhile, previous researches show that there are oscillations of the transmission intensity of electrons with time in the glass capillaries with outer serface having no grounded conductive shielding, So, the application of glass capillary to making the microbeam of electrons is limited.</sec><sec>In this paper, the transmission of 1.5 and 0.9 keV electrons through the glass capillary without/with the grounded conductive-coated outer surface are investigated, respectively. This study aims to understand the mechanism for low energy electron transport in the glass capillaries, and find the conditions for the steady transport of the electrons. Two-dimensional angular distribution of the transported electrons and its time evolution are measured. It is found that the intensity of the transported electrons with the incident energy through the glass capillaries for the glass capillaries without and with the grounded conductive-coated outer surface show the typical geometrical transmission characteristics. The time evolution of the 1.5- keV electron transport presents an extremely complex variation for the glass capillary without the grounded conductive-coated outer surface. The intensity first falls, then rises and finally oscillates around a certain mean value. Correspondingly, the angular distribution center experiences moving towards positive-negative-settlement. In comparison, the charge-up process of the 0.9 keV electron transport through the glass capillary with the grounded conductive-coated outer surface shows a relatively simple behavior. At first, the intensity declines rapidly with time. Then, it slowly rises till a certain value and stays steady subsequently. The angular distribution of transported electrons follows the intensity distribution in general, but with some delay. It quickly moves to negative direction then comes back to positive direction. Finally, it regresses extremely slowly and ends up around the tilt angle. To better understand the physics behind the observed phenomena, the simulation for the interaction of the electrons with SiO<sub>2</sub> material is performed to obtain the possible deposited charge distribution by the CASINO code. Based on the analysis of the experimental results and the simulated charge deposition, the conditions for stabilizing the electron transport through glass capillary arepresented.</sec>

Transmission and Trapping of Low-Energy (1–10 eV) Electrons in Crystalline Ice Films

We studied the interactions between low-energy (1–10 eV) electrons and a crystalline ice film in a low fluence condition, where incident electrons interacted mostly with the pristine ice lattice. The electron beams were irradiated onto an ice film sample of large thickness (>100 monolayers) at 95 K. The kinetic energy and flux of incident electrons were maintained constant by applying an offset bias potential to the sample to compensate the charging voltage of an ice film developed by electron trapping. A Kelvin work-function probe was used to measure the charging voltage and estimate the electron trapping efficiency. The measurements for ice films with different thicknesses showed that low energy electrons transmitted through the ice films very efficiently. When electrons were trapped in the ice films, the trapping occurred preferentially at the surface of ice films. The electron trapping cross-section for the ice surface was estimated to be ≤(2.6 ± 0.3) × 10–23 m2 at the incident electron energy of 1–10 eV. The electron trapping cross-section for the ice interior was below ∼10–25 m2. In comparison, adsorbed SO2 and CFCl3 molecules on the ice surface were able to trap incident electrons much more efficiently than the surface water molecules, with corresponding cross sections of (1.1 ± 0.4) × 10–21 m2 and (2.8 ± 0.3) × 10–21 m2, respectively.

Electron transmission through a steel capillary

Abstract The transmission of low-energy electrons through a macroscopic steel capillary has been investigated both experimentally and theoretically. The length of the steel capillary was L = 19.5 mm and the inner diameter was d = 0.9 mm. The kinetic energy distribution of electrons transmitted through the steel capillary was recorded for a tilt angle of ψ = 2.6 ° of the incident electron beam with respect to the capillary axis. Accompanying simulations based on classical transport theory reproduce the experimental data to a high degree of agreement. Transmission for other tilt angles has also been simulated to investigate the influence of the tilt angle on the guiding efficiency.

Transmission of low-energy electrons through ultrathin layers of tin(IV) phthalocyanine oxide

The results of the investigation of the transmission of low-energy electrons through 8-nm-thick films of tin(IV) phthalocyanine oxide (SnOPc) on the surface of the oxidized silicon substrate are presented. The procedure of detecting the reflection of testing low-energy electron beam from the surface was implemented using the very low-energy electron diffraction (VLEED) technique in the total current spectroscopy (TCS) mode with a change in the incident electron beam energy from 0 to 25 eV. The structure of maxima in the total current spectra of SnOPc films was established and the variation in intensities of the maxima of total current spectra emitted from the deposited SnOPc film and (SiO2)n-Si substrate during an increase in the thickness of the organic coating to 8 nm was analyzed. With such an increase in the thickness of the organic coating, the work function of the surface increases by 0.7 eV, which corresponds to the transfer of the electron density from the (SiO2)n-Si substrate to the SnOPc film. Optical absorption spectra of SnOPc films were measured. The absorption spectra were compared with the spectra measured by the TCS method for the SnOPc films and the films of molecules of oxygen-free metal phthalocyanine.

Guiding of Electrons through a Paired Parallel Glass Plates

We investigate transmission of low-energy electrons (800 eV) through a paired parallel glass plates. The measurements were focused on the angular distributions of electrons transmitted through capillary. The present results indicate that the observation angle ϕ is larger than the tilted angle ψ.

Characterization of 200 eV electrons transmission through a single glass microcapillary at large tilt angles

Transmission of low-energy electrons of 200 eV through a single glass capillary was investigated. The results show transmission of electrons at large tilt angles, where direct transmission should be geometrically prevented, thus indicating the existence of the guiding effect. Nevertheless, the transmitted current intensity was found to vary in time, while beside the dominant elastic peak, a significant contribution of inelasticlly scattered electrons was also obtained.

Transmission of electrons through Al2O3 nanocapillaries

We investigate transmission of low-energy electrons (250 eV) through insulating Al2O3 nanocapillaries (270 nm diameter and 15 μm length). Kinetic energy distribution of electrons transmitted through the nanocapillaries in the straightforward direction, time dependence of the transmission rate both in the straightforward direction and for tilted capillaries and angular distributions of electrons transmitted at the incident energy are presented and discussed.

Charging dynamics in electron transmission through Al2O3 capillaries

We have measured the transmission of low-energy (E=250eV) electrons through insulating Al2O3 nanocapillaries. We find that transmission at the incident energy is quickly suppressed with increasing tilt angle ψ of the capillary axis relative to the incoming electron beam while inelastic transmission becomes more important. For small angles of incidence charging dynamics lead to a decrease of total transmission (elastic and inelastic) with time. Our results are interpreted on the basis of a microscopic model for the electron transport within the capillary including also close interactions with the capillary wall.

Transmission of low-energy electrons through SiO2 tube

The transmission of low-energy (1100eV-1500eV) electrons through SiO2 tube was investigated, the distribution of transmitted beam current was observed. Results indicate that the intensity of transmitted electrons is proportional to the relative incident beam intensity and the angular divergence of the transmitted electrons is reduced when incident energy increased.

Fano resonances in low-energy electron transmission through crystalline films

It is shown that in crystalline films with a definite lattice symmetry there existone-dimensional bands of bound electron states above the boundary of the continuousspectrum. The intensity of electron reflection near the state of complete transmission oflow-energy electrons is found to have the form of a Fano resonance. We obtain therelationship between the Fano function parameters and physical characteristics of thesystem. The conditions for the electron transparency to arise near the bound state bands inthe continuum are determined.

Transmission of low-energy electrons in boron-doped nanocrystalline diamond films

Transmission electron spectroscopy is used to examine the low-energy electron transport and emission properties of nanocrystalline chemical-vapor-deposited diamond films. In particular, the intensity and energy distribution of transmitted electrons are measured as a function of film thickness and incident-beam parameters. Low-energy transmission is detected in measurements from two films of thickness 0.15 and 2.5 μm with similar boron concentrations. The transmitted energy distributions are very similar for the two samples and are nearly identical to those obtained in reflection measurements. The full width at half maximum of the transmitted distribution is slightly broader for the thinner film (∼0.8−0.9 eV) than for the thicker film (∼0.6−0.7 eV), and the maximum transmission yields are similar (∼3−5 emitted electrons per incident electron). However, different beam energies are required to produce the low-energy transmission. The energy-dependent data is interpreted using Monte Carlo simulations along with a qualitative model of the diamond nanostructure. From this analysis, the low-energy-electron escape depth is confirmed to be as long as ∼1 μm in the 2.5-μm-thick sample.

Electron transmission studies of diamond films

Diamond is an attractive cold emitter candidate because of specific negative-electron-affinity (NEA) surfaces and good electron transport properties. In this study, transmission electron spectroscopy is used to examine the low-energy electron transport and emission properties of thin CVD diamond films. After injecting electrons into diamond films using an external electron gun, the transmission of low-energy secondary electrons is examined. In particular, the intensity and energy distribution of the transmitted electrons are measured as a function of the film properties (thickness, doping concentration) and incident beam properties (energy, intensity). Electron transmission through a heavily-doped, 5μm thick film exhibits a larger energy spread and lower intensity than electron transmission through a medium-doped, 2μm thick film. However, the transmission yields are relatively low for both films compared to the reflected yield measurements. Furthermore, the incident beam parameters influence the transmitted electron distribution in ways that cannot be explained by our secondary emission model. On the other hand, the results of the study concerning the transmission of high-energy electrons confirm the theoretical predictions of electron penetration depths in diamond. These initial electron transmission measurements from thin diamond films indicate that the transport process is quite complex, and the study reveals several issues that need to be examined further before the cold emission capabilities of diamond can be assessed.

Transmission of Low-Energy Electrons through Polycrystalline LiF Films

physica status solidi (b)Volume 216, Issue 2 p. R1-R2 Rapid Research Note Transmission of Low-Energy Electrons through Polycrystalline LiF Films F. Gołek, F. Gołek Institute of Experimental Physics, University of Wrocław, Pl. Maxa Borna 9, 50-204 Wrocław, PolandSearch for more papers by this authorW.J. Sobolewski, W.J. Sobolewski Institute of Experimental Physics, University of Wrocław, Pl. Maxa Borna 9, 50-204 Wrocław, PolandSearch for more papers by this author F. Gołek, F. Gołek Institute of Experimental Physics, University of Wrocław, Pl. Maxa Borna 9, 50-204 Wrocław, PolandSearch for more papers by this authorW.J. Sobolewski, W.J. Sobolewski Institute of Experimental Physics, University of Wrocław, Pl. Maxa Borna 9, 50-204 Wrocław, PolandSearch for more papers by this author First published: 02 December 1999 https://doi.org/10.1002/(SICI)1521-3951(199912)216:2<R1::AID-PSSB99991>3.0.CO;2-HCitations: 6AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume216, Issue2December 1999Pages R1-R2 RelatedInformation

Electron Transmission Through Thin Organized Organic Films

The interaction between electrons and organized organic thin films was investigated by measuring the energy distribution of photoelectrons injected from a thin silver film coated with thin organic layers. Electrons with energy above ∽0.8 eV were transmitted ballistically through an organic layer that contains up to five monolayers, each ∽2 nm thick. Elastic scattering processes contribute significantly to the electron energy distribution only for thicker layers. The transmission of low-energy electrons is controlled mainly by an electrostatic barrier perpendicular to the surface. A signature of a band structure in the organic layer was observed when the electrons were transmitted through 13 layers. © 1997 by John Wiley & Sons, Ltd.

Photoemission through thin dielectric coating films

Photoemission through thin coating films was studied in the scope of protection of sensitive photocathodes. The transmission of low energy (∼1 eV) electrons was measured for a large number of dielectric films (LiF, NaF, CsF, NaI, MgF2, BaF2, SiO, SiO2, Al2O3, n-C36H74), evaporated in vacuum on CsI and CuI photocathodes. Some films like CsF, NaI and n-C36H74 were found to have a fairly large electron attenuation length, varying from about 20 to 100 Å at a maximum initial electron energy of 1 eV. A thin CsF layer deposited on top of CuI and Al photocathodes was found to significantly increase their quantum yield. An enhancement of the photoyield following exposure to water vapour was observed for alkali fluoride-coated photocathodes. We interpret this effect as a decrease of the electron affinity by about 0.3–0.4 eV, induced by adsorption of polarized H2O dipoles.

The interactions of electrons with organized organic films studied by photoelectron transmission

The interaction between electrons and organized organic thin films was investigated by measuring the energy distribution of photoelectrons injected from a thin silver film coated with thin organic layers. Electrons with an energy above approximately 0.8 eV were transmitted ballistically through an organic layer containing up to five monolayers each about 2 nm thick. The transmission of low-energy electrons is controlled mainly by an electrostatic barrier perpendicular to the surface. Both elastic and nonelastic scattering were found to be unimportant on the scale of a single monolayer. The mean free path for electrons with an energy of 1.15 eV was found to be about 26 nm.

Spin-dependent transmission of low-energy electrons through ultrathin magnetic layers.

We present an experiment in which the attenuation of a spin-polarized free electron beam is measured by direct transmission through an ultrathin ferromagnetic layer. The self-supported metal target consists of a 1-nm-thick cobalt film sandwiched between 21- and 2-nm-thick gold layers. Measurements are performed throughout a wide energy range (incident electron energies from 4 eV to 50 eV above the Fermi level). At low energy, close to the clean surface vacuum level, we find that the transmission coefficient of minority spin electrons is about 0.7 times that of majority spin electrons.

Transmission of low energy electrons through aluminum films

Abstract The spectrum of electrons transmitted through an aluminum film in the case of low energy electron (<10 keV) incidence has been investigated. Both the energy loss straggling due to inelastic interactions and the angular distribution due to elastic interactions were considered. Calculations have been made based on several theoretical methods with inelastic and elastic scattering crosssections obtained from, respectively, the electron gas model and the Hartree-Fock-Wigner-Seitz model. Results of our calculations were compared with the experimental data.

Theoretical study of the transmission of low-energy (0–10 eV) electrons through thin-film organic molecular solids: Benzene

A theoretical study of the transmission of low-energy (0–10 eV) electrons incident from vacuum through thin-film organic molecular solids deposited on a cold metal substrate is presented and developed for the specific case of solid benzene. In essence, using a semiclassical description of electron transport in solids with an energy-independent scattering mean free path and assuming an isotropic electron scattering, the behavior of a penetrating electron in the film is simulated when a large number of scattering events are present. The good agreement between the calculated electron transmission spectra and those obtained experimentally indicates that our study provides a realistic description of the electron transport in the film, and accounts for the influence of the various electron-molecule scattering processes upon the energy dependence of the transmitted current. In particular, we show that the excitonic subionization energy losses are at the origin of the main structures of the observed electron transmission spectra. It is also shown that our study can successfully be used to estimate the probabilities of the various electron scattering processes which occur in the film, as well as the electron mean free path l. For solid benzene, l is about 8 Å in the considered electron energy range.

Low-energy (0–10 eV) electron transmission through solid thin benzene films

A theoretical study of the transmission of low-energy (0–10 eV) electrons incident from vacuum through thin-film molecular solids deposited on a cold metal substrate is presented for the specific case of solid benzene. Using a semi-classical description of electron transport in solids with an energy-independent scattering mean free path and assuming an isotropic electron scattering, the behavior of a penetrating electron in the film is simulated when a large number of scattering events is present. The good agreement obtained between the calculated electron transmission spectra and those observed experimentally shows that our study can successfully be used to determine the probabilities of the various electron scattering processes which occur in the film, as well as the electron mean free path ( l). For solid benzene, l ≈ 8 Å in the investigated electron energy range.