Aplicação do novo método de fluxo relativo na determinação das seções de choque diferenciais elásticas para o espalhamento de elétrons de baixa energia por álcoois e pela água

Abstract

In this work were performed measurements of Elastic Differential Cross Section (EDCS) for low energy by polyatomic molecules electron scattering using a new version of Relative Flow Method (RFM) associated to an aperture coupled in a movable tube as a source of gas. This technique was developed by M. A. Khakoo et al. In this new RFM the EDCSs are obtained without any previous information about kinetic molecular diameter of the gas in study. That modification allowed us apply the new RFM more accurately and faster than the conventional RFM and also, apply it to several compounds which were not possible to be studied previously. The measurements of EDCS were obtained for alcohols molecules as methanol, ethanol, n-propanol e n-butanol, whose molecular diameters were not published in the literature, generating new information about these targets. The energetic range worked was from 1 to 100 eV and the scattering angles from 5 to 130°. Additional measurements of EDCS were obtained for H2 e N2 to provide a excellent test to the new RFM. The data for these molecules are in excellent agreement with compared data from literature, thus theoretical as experimental showing the excellence of the new technique and the performance of spectrometer. In an additional test for the RFM, measurements of EDCS for water vapor were registered. However, these measurements are in a big quantitative disagreement with experiments developed in the past witch applied the conventional RFM. This discrepancy took to questioning of the measurements of EDCS previously published for water in the literature suggesting to the scientific community that EDCS data for water be revised despite the kinetic molecular diameter found in our experiment showed bigger (1.8 times) than those published in the past.