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A. R. Milosavljević |
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Physics - Thesis - Ph. D. Thesis |
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FACULTY
OF PHYSICS Aleksandar R. Milosavljević Electron
interaction with DNA deoxyribose analogue molecules Ph.D. THESIS Belgrade, 2006. (written in Serbian) ABSTRACT The experimental investigation of electron
interaction with molecules tetrahydrofuran (THF) and tetrahydrofurfuryl
alcohol (THFA), at medium incident electron energies (30-300 eV), is
presented. The obtained results cover elastic scattering, electron energy
loss spectra and kinetic energy distribution of positive ionic fragments,
formed upon electron-induced ionization. Absolute differential cross sections (DCSs) for
elastic electron scattering by THF and THFA are tabulated in small energy and
angular steps. An experimental procedure allowing independent measurements of
relative DCSs as a function of either scattering angle or incident electron
energy, is described in detail. Generally, the DCSs for THF and THFA appear
to be rather similar, both in shape and on the absolute scale. The relative
DCSs are in good agreement with recent theoretical data, except in the region
around the minimum. The electron energy loss spectra (EELS) are
measured for different incident electron energies, at different scattering
angles (ł10o), with the energy resolution of about 0.5 eV. In the case
of THF, a very good agreement with previous both VUV photo-absorption spectra
and high resolution EELS, is obtained. Furthermore, the EELS at higher both
incident electron energies and scattering angles are presented for the first
time. To the best of our knowledge, the first EELS for THFA are presented in
this work. The latter appear to be rather similar to THF spectra and can be
fitted to Ridberg series. The obtained energy levels are in a very good
agreement with the most recent (still unpublished) VUV data. The kinetic energy distributions of positive
ionic fragments, formed upon electron induced ionization (dissociation) of
THF and THFA, are obtained for different incident electron energies and
different detection angles in reference to the incident electron beam. These
are the first measurements of this type for THF and THFA. The abundance of
ions with higher kinetic energies (1-4 eV) increases, while the abundance of
ions with lower energies decreases, with increasing the incident electron
energy. The signal of low-energy fragments decreases, while the signal of
high-energy ions increases, with increasing the detection angle in reference
to the incident electron beam. The THF and THFA molecules can be considered as
simple analogues to DNA sugar deoxyribose. Therefore, the present results are
of interest for investigation of radiation damage in living tissue upon
exposure to high-energy radiation. The cross-section data set is of interest
in estimating and modeling of products production processes, induced by
electrons within a molecular sample. In particular, the electron scattering
cross-sections, both differential and integral, are the input parameters for
energy deposition modeling that is based on a Monte Carlo simulation of the
single electron scattering process. USEFUL REFERENCES A. R. Milosavljević, S. Madžunkov, D. Šević, I. Čadež and B. P. Marinković, J. Phys. B: At. Mol. Opt. Phys. 39,
609-623 (2006)
A.R. Milosavljević, A.
Giuliani, D. Ševic, M.J. Hubin-Franskin and B.P. Marinković, Eur. Phys. J. D 35, 411-416 (2005) SOME RESULTS
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