Elastic scattering of electrons from alanine

Differential cross sections (DCSs) for elastic scattering of electrons from alanine, have been measured using a crossed beam system for incident energies between 20 and 80 eV and scattering angles from 10° to 150°. The experimental data were placed upon an absolute scale by normalisation to calculated absolute integral cross sections obtained using the corrected independent-atom method incorporating an improved quasifree absorption model. The calculated data-set includes DCSs and integral elastic and inelastic cross sections in the incident energy range between 1 and 10,000 eV. These theoretical results are found to agree very well with the experimental data both in the shape and magnitude of DCSs except at the smallest scattering angles

Absolute cross sections for elastic electron scattering from methylformamide

Elastic electron scattering from gaseous methylformamide (N-methylformamide, C 2H 5NO) has been investigated. Absolute elastic differential cross sections (DCSs) were determined both experimentally and theoretically for the incident energies from 50 to 300 eV. The measurements were performed using a cross-beam technique, for scattering angles from 20° to 110°. Relative elastic DCSs were measured as a function of both the angle and the incident energy and the absolute DCSs were determined using the relative flow method. The calculations of electron interaction cross sections are based on a corrected form of the independent-atom method, known as the SCAR (screen corrected additivity rule) procedure and using an improved quasifree absorption model. Calculated integral cross sections have been presented, as well, both for methylformamide and formamide, in the energy range 10-1000 eV, and discussed. The results are compared with and discussed regarding existing data for other small molecules representing building blocks of large biomolecules. © 2012 American Physical Society.The work was supported by the Ministry of Education and Science of Republic of Serbia (Project No. 171020) and Spanish Ministerio de Ciencia e Innovacion Project No FIS2009-10245, and motivated by the COST Action MP1002 (Nano-IBCT).Peer Reviewe

DOPING OF NANO-SIZED DIAMOND LIKE CARBON FILMS AND THEIR CHARACTERIZATION BY MICRO RAMAN SPECTROSCOPY

Capabilities of the rf plasma beam source in deposition of ultra thin diamond like carbon for the hard disk drive applications have been studied. Nano-sized films were doped by nitrogen, hydrogen and silicon and characterized by micro Raman spectroscopy. Projected ranges of incident carbon ions into the magnetic layer as well as growing film were calculated by Monte Carlo simulation. Ion ranges at 100 eV incident energy were around 0.5 nm. With micro Raman spectroscopy is possible to qualitatively determine optimal deposition parameters and to follow changes in the film properties and carbon binding structure in amorphous matrix with hydrogen, nitrogen and silicon doping elements

Absolute differential cross sections for elastic scattering of electrons from pyrimidine

7 pags. ; 3 figs. ; 1 tab.Differential cross sections DCSs for elastic scattering of electrons from pyrimidine C4 H4 N2 are presented for incident energies from 50 to 300 eV. The measurements were performed using a cross beam technique, for scattering angles from 20° to 110°. The relative DCSs were measured as a function of both the angle and incident energy and the absolute DCSs were determined using the relative flow method. The calculations of electron interaction cross sections are based on a corrected form of the independent-atom method, known as the screen corrected additivity rule procedure and using an improved quasifree absorption model. Calculated results agree very well with the experiment. ©2009 The American Physical SocietyThis work was supported through Project No. 141011 fi- nanced by the Ministry of Science and Technological Development of Republic of Serbia and the Spanish Ministerio de Ciencia e Innovacion Project No. FISI2006-00702 . The present work was also motivated by research within COST Actions P9 “Radiation Damage in Biomolecular Systems” and CM0601 “Electron Controlled Chemical Lithography ECCL .”Peer reviewe

Absolute cross sections for electron scattering from furan

We report results of measurements and calculations of absolute cross sections for electron scattering from furan molecules (C 4H 4O). The experimental absolute differential cross sections (DCSs) for elastic electron scattering were obtained for the incident energies from 50 eV to 300 eV and for scattering angles from 20 to 110, by using a crossed electron-target beam setup and the relative flow technique for calibration to the absolute scale. The calculations of the electron interaction cross sections are based on a corrected form of the independent-atom method, known as the screening corrected additivity rule (SCAR) procedure and using an improved quasifree absorption model. The latter calculations also account for rotational excitations in the approximation of a free electric dipole and were used to obtain elastic DCSs as well as total and integral elastic cross sections which are tabulated in the energy range from 10 to 10 000 eV. All SCAR calculated cross sections agree very well with both the present and previously published experimental results. Additionally, calculations based on the first Born approximation were performed to calculate both elastic and vibrationally inelastic DCSs for all the modes of furane, in the energy range from 50 eV to 300 eV. The ratios of the summed vibrational to elastic DCSs are presented and discussed. Finally, the present results for furan are compared with previously published elastic DCSs for the tetrahydrofuran molecule and discussed. © 2012 American Institute of Physics.American Institute of Physics#Supported by the Ministry of Education and Science of Republic of Serbia (Project No. 171020) and Spanish Ministerio de Ciencia e Innovación Project No. FIS2009-10245, and motivated by the COST Action MP1002 (Nano-IBCT). R.C. acknowledges support of the Czech Ministry of Education (Grant No. OC10046) and the Grant Agency of the Czech Republic (Grant No. P208/11/0452).Peer Reviewe

Development of collisional data base for elementary processes of electron scattering by atoms and molecules

We present a progress report on the development of the Belgrade electron/molecule data base which is hosted by The Institute of Physics, University of Belgrade and The Astronomical Observatory Belgrade. The data base has been developed under the standards of Virtual Atomic Molecular Data Centre (VAMDC) project which provides a common portal for several European data bases that maintain atomic and molecular data. The Belgrade data base (BEAMDB) covers collisional data of electron interactions with atoms and molecules in the form of differential (DCS) and integrated cross sections as well as energy loss spectra. The final goal of BEAMDB becoming both a node within the VAMDC consortium and within the radiation damage RADAM data base has been achieved

Communication: "Position" does matter: The photofragmentation of the nitroimidazole isomers

A combined experimental and theoretical approach has been used to disentangle the fundamental mechanisms of the fragmentation of the three isomers of nitroimidazole induced by vacuum ultra-violet (VUV) radiation, namely, 4-, 5-, and 2-nitroimidazole. The results of mass spectrometry as well as photoelectron-photoion coincidence spectroscopy display striking differences in the radiation-induced decomposition of the different nitroimidazole radical cations. Based on density functional theory (DFT) calculations, a model is proposed which fully explains such differences, and reveals the subtle fragmentation mechanisms leading to the release of neutral species like NO, CO, and HCN. Such species have a profound impact in biological media and may play a fundamental role in radiosensitising mechanisms during radiotherapy

BEAMDB and MolD – databases for atomic and molecular collisional and radiative processes: Belgrade nodes of VAMDC

Abstract: We present two atomic and molecular (A&M) databases, MolD and BEAMDB, hosted by the SerVO – the Serbian virtual observatory (http://servo.aob.rs). These databases and web applications have been implemented in accordance to the standards developed by Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu). The MolD database contains photo-dissociation cross-sections for individual rovibrational states of the diatomic molecular ions and rate coefficients for the atom-Rydberg atom chemi-ionisation and inverse electron-ion-atom chemi-recombination processes. The Belgrade electron/atom(molecule) database (BEAMDB) provides collisional data for electron interactions with atoms and molecules. Differential cross sections (DCS) are presented for both elastic and inelastic (excitation) cross sections in tabulated data tables. These DCS data are integrated over a full range of scattering angles in order to achieve integral, momentum transfer and viscosity cross sections as functions of impact electron energy. Beside these tables, energy loss spectra are presented in the graphical form