Attenuating mediums, targets and barriers made of submicronic layers with low average atomic number （low Z） and minimal electronic density that reduces the elastic scattering and absorption of radiation are required...Attenuating mediums, targets and barriers made of submicronic layers with low average atomic number （low Z） and minimal electronic density that reduces the elastic scattering and absorption of radiation are required for many applications. This work describes the development and characterization of submicronic Lexan （Polycarbonate） polymer foils with low Z for two new electron inelastic mean free path assessment methods. Lexan layers with thicknesses of 120 nm to 240 nm were developed and fabricated using spin coating. The submicronic layers were characterized by AFM and CSI for thickness, roughness and levelness. Roughness was found to be 1.0-2.4 nrn rms, and the change in total thickness was within ＋ 7.5%. The results of total current measurements using 177 nm Lexan foil irradiated under an SEM electron beam were compared to those for a similar polymer foil. The first step of a wide spectrum method experiment was performed at the ESRF using Lexan submicronic layers on a silicon substrate. The signal peak and the multiple inelastic scattering peak of the Lexan spectrum was similar to those previously measured on carbon films. This study supported the suitability of the developed Lexan films for electron scattering measurements.展开更多
HAXPES （hard X-ray photoelectron spectroscopy） is a powerful emerging instrument in surface analysis. It extended the photoelectron energy range up to 15,000 eV and opened the possibility to study much thicker films...HAXPES （hard X-ray photoelectron spectroscopy） is a powerful emerging instrument in surface analysis. It extended the photoelectron energy range up to 15,000 eV and opened the possibility to study much thicker films, buried layers and bulk electronic properties. In order to study these features, data for the electron IMFP （inelastic mean free path） at these energies is needed. To date, only calculated IMFP are available at energies above 5,000 eV and therefore experimental validation of these calculations are essential. In this paper, a new approach for using the HAXPES spectra is presented. This approach, treats the attenuated part of the electron spectrum as a whole to calculating the average electron energy loss. This average electron energy loss is the result of inelastic collisions in the material and hence, carry with it information about the electron transport poses. Carbon layers with thicknesses between 20 and 75 nanometer deposited over copper substrate were used to test this approach at the Spanish beam-line （Spline） in the ESRF （European synchrotron radiation facility）. The measured results showed good agreement with the predictions of the multiple inelastic scattering theory. In addition, an algorithm for the experimental evaluation of electron IMFP, using the measured energy loss, is proposed.展开更多
文摘Attenuating mediums, targets and barriers made of submicronic layers with low average atomic number （low Z） and minimal electronic density that reduces the elastic scattering and absorption of radiation are required for many applications. This work describes the development and characterization of submicronic Lexan （Polycarbonate） polymer foils with low Z for two new electron inelastic mean free path assessment methods. Lexan layers with thicknesses of 120 nm to 240 nm were developed and fabricated using spin coating. The submicronic layers were characterized by AFM and CSI for thickness, roughness and levelness. Roughness was found to be 1.0-2.4 nrn rms, and the change in total thickness was within ＋ 7.5%. The results of total current measurements using 177 nm Lexan foil irradiated under an SEM electron beam were compared to those for a similar polymer foil. The first step of a wide spectrum method experiment was performed at the ESRF using Lexan submicronic layers on a silicon substrate. The signal peak and the multiple inelastic scattering peak of the Lexan spectrum was similar to those previously measured on carbon films. This study supported the suitability of the developed Lexan films for electron scattering measurements.
文摘HAXPES （hard X-ray photoelectron spectroscopy） is a powerful emerging instrument in surface analysis. It extended the photoelectron energy range up to 15,000 eV and opened the possibility to study much thicker films, buried layers and bulk electronic properties. In order to study these features, data for the electron IMFP （inelastic mean free path） at these energies is needed. To date, only calculated IMFP are available at energies above 5,000 eV and therefore experimental validation of these calculations are essential. In this paper, a new approach for using the HAXPES spectra is presented. This approach, treats the attenuated part of the electron spectrum as a whole to calculating the average electron energy loss. This average electron energy loss is the result of inelastic collisions in the material and hence, carry with it information about the electron transport poses. Carbon layers with thicknesses between 20 and 75 nanometer deposited over copper substrate were used to test this approach at the Spanish beam-line （Spline） in the ESRF （European synchrotron radiation facility）. The measured results showed good agreement with the predictions of the multiple inelastic scattering theory. In addition, an algorithm for the experimental evaluation of electron IMFP, using the measured energy loss, is proposed.
