CONICET | Buscador de Institutos y Recursos Humanos

PÓSTERThe ionization cross section sigma by electron impact in the nitrogen K-shell is a parameter of interest in atomic physics and in several spectroscopic techniques, although experimental determinations for this parameters are quite scarce. In the present work, sigma values were obtained from the x-ray spectra produced in a thin AlN target, assuming that the influence of the chemical bonding is negligible, as it was find previously for oxygen within the experimental uncertainties. The AlN film was deposited on a vitreous carbon planchet, by ion magnetron sputtering with an ultrahigh vacuum equipment (AJA International ATC Orion 8). The mass thicknesses of the films were determined using Rutherford Backscattering Spectrometry with the ion accelerator TANDEM 3MV at the Instituto de Física of the Univ. Federal do Rio Grande do Sul. X-ray emission spectra excited by electron incidence were measured in a JEOL JXA 8230 microprobe with a wavelength dispersive spectrometer at the Laboratorio de Microscopía Electrónica y Análisis por Rayos X of the Univ. Nacional de Córdoba, Argentina. The absolute determination of sigma requires not only the measurement of the film mass thickness, but also the knowledge of the spectrometer efficiency; for the determination of this efficiency, a method developed previously was applied to the equipment used here, and the solid angle subtended by the x-ray detector also had to be determined. To this end, the bremsstrahlung generated between 3 and 6 keV by an aluminum substrate when irradiated with 15 keV electrons was simulated with the PENELOPE software. By comparing the experimental spectrum with the simulated values, the solid angle was determined. Once the needed parameters were obtained, the ionization cross section was calculated from the nitrogen K peak intensities of the experimental spectra.