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Measurements of the optical properties of liquid water were extended in the vacuum ultraviolet up to an energy of 25.6 eV. The indices of refraction and dielectric functions were obtained by a Kramers-Kronig analysis using reflectances measured in this study between 7.6 and 25.6 eV and reflectances from the literature below 7.6 eV. Our interpretation of the prominent peak in the energy loss function at about 21 eV is that it represents a collective electronic oscillation.

Monte Carlo computer models that simulate the detailed, event-by-event transport of electrons in liquid water are valuable for the interpretation and understanding of findings in radiation chemistry and radiation biology. Because of the paucity of experimental data, such efforts must rely on theoretical principles and considerable judgment in their development. Experimental verification of numerical input is possible to only a limited extent. Indirect support for model validity can be gained from a comparison of details between two independently developed computer codes as well as the observable results calculated with them. In this study, we compare the transport properties of electrons in liquid water using two such models, PARTRAC and NOREC. Both use interaction cross sections based on plane-wave Born approximations and a numerical parameterization of the complex dielectric response function for the liquid. The models are described and compared, and their similarities and differences are highlighted. Recent developments in the field are discussed and taken into account. The calculated stopping powers, W values, and slab penetration characteristics are in good agreement with one another and with other independent sources.

Articles you may be interested inQuantitative analysis of electron energy loss spectra and modelling of optical properties of multilayer systems for extreme ultraviolet radiation regime Optical constants of dry films of deoxyribonucleic acid (sodium salt of calf thymus DNA) have been determined in the 2-82 eV region of photon energy. The extinction coefficient k was obtained by transmission measurements on thin films on metal mesh screens. The refractive index n in the nonabsorbing region 2--4 eV was obtained from critical-angle measurements on films deposited on a sapphire semicylinder. To determine the value of n above 4 eV, a Kramers-Kronig analysis was performed using the measured values of k. From these optical constants the complex dielectric function E and the energy-loss function for charged particles -Im(l/E) were derived. The results exhibit, in addition to the well-established absorptions around 4.7 and 6.5 eV, a strong absorption at 13.8 eV and a prominent peak in the energy-loss function at 21.6 eV which exhibits a large degree of collective behavior.