Table of contents

The novel approach of DNA origami structures as templates for precise quantification of various well- defined oligonucleotides provides the opportunity to determine the sensitivity of complex DNA sequences towards low-energy electrons.

Resonant formation of H^- and O^- ions and formation of ethylene glycol (OHCH₂CH₂OH) on electron impact is seen in the same energy range in condensed molecular films of methanol (CH₃OH). This could indicate a new reaction pathway involving bond breaking and bond formation at specific electron energies in condensed methanol.

Ion desorption measurements induced by the impact of electrons onto pyridine and pyrimidine ices will be presented. The data reported here is of relevance for chemical evolution models of astrophysical objects.

Methyl cyanide (CH₃CN) is the simplest organic nitrile and it is found in almost all astrophysical environments, including cometary comae, Titan's atmosphere and the interstellar medium (ISM), especially in starforming regions and hot cores. In this work, the role of ion desorption caused by electron collisions onto a CH₃CN ice is discussed. New ionic species, including ion clusters are produced, pointing to the delivery of more complex species from ice surfaces to the gas-phase in the ISM.

The new experiments on channeling of 255 MeV in a 0.7 μm silicon half-wavelength crystal were performed at SAGA LS facility. Both experimental and simulated electron angular distribution after the crystal and corresponding radiation spectra reveal the number of peculiarities.

We investigate electron attachment to chemisorbed and physisorbed L-cysteine/Au(111) films and its subsequent dissociation via electron stimulated desorption (ESD) measurements; More specifically, dissociative electron attachment (DEA) which in essentially, molecular dissociation into a neutral and anionic fragment following initial electron capture into short-lived molecular anion or resonance leads to the rupture of specific bonds, if the incident electron energies are within characteristic ranges (below 20 eV).

We analyze the asymmetry found in the production of plasmons by fast charged particles entering or leaving a semi-infinite material through a planar surface. In the framework of a semiclassical dielectric formulation, we study how this effect depends on the angle of incidence.

We address the problem of quantifying the decay of plasmons excited in the electron gas of a condensed medium. Within the dielectric formalism, we use various methods to define and assess the damping constant γ.

In this work we study the transmission of charged particles through a single cylindrically shaped metallic capillary of microscopic dimensions with a large aspect ratio. We used electrons as projectiles. Our results suggest the existence of guiding of the electron beam by a metallic capillary.

We have measured the electron stimulated desorption (ESD) yields of anions and cations from thin films of Fe(CO)₅ deposited onto both Xe or Pt surfaces. Measurements were made as functions of incident electron energy, incident current, and the thickness of both the Fe(CO)₅ and Xe layers. The desorption of C^- and O^- occur exclusively via dipolar dissociation (DD), while the desorption of Fe(CO)x^- (x = 0-4) proceeds via DD and dissociative electron attachment (DEA). Threshold energies for the desorption of cationic fragments C⁺, O⁺, CO⁺, and Fe(CO)⁺_x (x = 0-4) were measured. Only CO⁺ appears to be produced by DD as opposed to dissociative ionization.

Absolute cross sections (CSs) for vibrational excitation were obtained for low energy electron impact with tetrahydrofuran (THF) molecules condensed on Ar at 19K. The absolute CSs were measured with a high resolution electron energy loss spectrometer for the 1 to 19 eV incident electron energy range. The values of the vibrational CSs are found to lie within the 10^-17cm² range and to show the effects of resonant excitation.

We present Monte Carlo simulation of low energy electrons backscattered from iron (Fe) surface. We take into account both elastic and inelastic collisions during the simulation. In our simulations the primary electron energy is 150 eV and the incidence angle of the electron beam with respect to the surface is varied between 1° and 90 °. The backscattered electron energy loss distributions for primary and as well for secondary electrons and the distribution of maximum electron penetration depths in the Fe sample were calculated using only the bulk and also the surface dielectric function.

An extended reverse Monte Carlo (RMC) method for obtaining optical constants of ultrathin films and solids is presented. Our results show that this method works very well in extracting some exquisite information from experimentally measured reflection electron energy loss spectroscopy (REELS) spectra. The energy loss function (ELF) of 100 nm nickel film in a relatively larger energy loss range of 0-200 eV has been obtained, which agrees well with other computational data. Employing this ELF, individual contributions to REELS intensity due to surface and bulk plasmon excitations are quantitatively separated for further study.