Kamil Fedus

Properties and limitations of chalcogenide films

Two chalcogenide films with composition Ge25-Sb10+xS65 (x = 0, 10) and Te20As30Se50, called 2S1G and TAS, respectively, are studied. These materials have high linear and nonlinear refractive indices and present interesting photosensitive behavior toward bandgap light. Further, these chalcogenides glasses can be deposited in an amorphous thin ?lm for optical coatings or waveguides. Their properties and limitations, including their photoinduction effects, nonlinear Kerr effect, photodiffusion of silver, and aging, are discussed.

Some Systematics in Electron Scattering Cross Sections

Abstract Operation of thermonuclear reactors will require knowledge of numerous cross sections for electron interaction with atoms and molecules, largely unknown at present and difficult for experiments. Theory is needed, but first it has to be verified on laboratory-accessible targets. A few working hypotheses and systematic approaches for various electron scattering processes are recommended. We discuss briefly analogies between total cross sections for scattering on nonpolar (BF3, CO2), polar (H2O, NH3, PF3), reactive (BCl3, HCl), and hexafluoride (SF6, WF6) molecules. For partial cross sections (ionization, elastic, electronic excitation), we search for some partitioning schemes. Similarly, we treat the vibrational excitation at shape resonances in linear triatomic molecules (N2O, CO2, OCS). Electron attachment for targets such as CCl4 or CF3I rises quickly toward the zero-energy limit; semiempirical approaches fail, but new theories work well. The paper, in general, shows ways to multitask construction of cross sections rarely measured in laboratories.

Low-energy elastic electron scattering from chloromethane, CH3Cl

We report theoretical as well as (normalized) experimental differential and integral cross sections for vibrationally elastic scattering of low-energy electrons from chloromethane, CH_3Cl, also known as methyl chloride. The theoretical cross sections were computed using the Schwinger multichannel variational method in the single-channel approximation, with polarization effects included via virtual excitations. Cross section measurements were made at incident energies ranging from 0.5 to 100 eV and at scattering angles from 5° to 125°. We compare our data to earlier previous results for this molecule.

Low-energy elastic electron scattering form chloroethane, C2H5Cl

We report theoretical as well as (normalized) experimental differential and integral cross sections for vibrationally elastic scattering of low-energy electrons from chloroethane, C_2H_5Cl, also known as ethyl chloride. The theoretical cross sections were computed using the Schwinger multichannel variational method in the single-channel approximation, with polarization effects included via virtual excitations. Cross section measurements were made at incident energies ranging from 1 to 30 eV and at scattering angles from 10° to 125°. We compare our data to previous results for C_2H_5Cl and for the related molecule chloromethane.