Theoretical and experimental study on electron interactions with chlorobenzene: Shape resonances and differential cross sections

9 págs.; 6 figs.; 1 tab.In this work, we report theoretical and experimental cross sections for elastic scattering of electrons by chlorobenzene (ClB). The theoretical integral and differential cross sections (DCSs) were obtained with the Schwinger multichannel method implemented with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR). The calculations with the SMCPP method were done in the static-exchange (SE) approximation, for energies above 12 eV, and in the static-exchange plus polarization approximation, for energies up to 12 eV. The calculations with the IAM-SCAR method covered energies up to 500 eV. The experimental differential cross sections were obtained in the high resolution electron energy loss spectrometer VG-SEELS 400, in Lisbon, for electron energies from 8.0 eV to 50 eV and angular range from 7 to 110. From the present theoretical integral cross section (ICS) we discuss the low-energy shape-resonances present in chlorobenzene and compare our computed resonance spectra with available electron transmission spectroscopy data present in the literature. Since there is no other work in the literature reporting differential cross sections for this molecule, we compare our theoretical and experimental DCSs with experimental data available for the parent molecule benzene. Published by AIP Publishing.A.S.B., M.T.N.V., S.d’A.S., and M.H.F.B. acknowledge the Brazilian Agency Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), under CAPES/FCT Programme (Process No. 23038.002465/2014-87). M.T.N.V., S.d’A.S., and M.H.F.B. acknowledge support from the Brazilian Agency Conselho Nacional de Desenvolvimento Científico e Tecnológico. M.H.F.B. acknowledges support from Finep (under project CT-Infra), and M.T.N.V. from São Paulo Research Foundation (FAPESP). A.S.B., S.d’A.S., and M.H.F.B. acknowledge computational support from Professor Carlos M. de Carvalho at LFTC-DFis-UFPR and at LCPADUFPR and from CENAPAD-SP. F.F.S. acknowledges the Portuguese National Funding Agency FCT through researcher Contract No. IF-FCT IF/00380/2014 and together with P.LV. the research Grant No. UID/FIS/00068/2013. F.B. and G.G. acknowledge partial financial support from the Spanish Ministry MINECO (Project No. FIS2012-31230).Peer Reviewe

Experimental and theoretical electron-scattering cross- section data for dichloromethane

We report on a combination of experimental and theoretical investigations into the elastic differential cross sections (DCSs) and integral cross sections for electron interactions with dichloromethane, CH₂Cl₂, in the incident electron energy over the 7.0-30 eV range. Elastic electron-scattering cross-section calculations have been performed within the framework of the Schwinger multichannel method implemented with pseudopotentials (SMCPP), and the independent-atom model with screening-corrected additivity rule including interference-effects correction (IAM-SCAR+I). The present elastic DCSs have been found to agree reasonably well with the results of IAM-SCAR+I calculations above 20 eV and also with the SMC calculations below 30 eV. Although some discrepancies were found for 7 eV, the agreement between the two theoretical methodologies is remarkable as the electron-impact energy increases. Calculated elastic DCSs are also reported up to 10000 eV for scattering angles from 0⁰ to 180⁰ together with total cross section within the IAM-SCAR+I framework

Theoretical and experimental study on electron interactions with chlorobenzene: Shape resonances and differential cross sections

In this work, we report theoretical and experimental cross sections for elastic scattering of electrons by chlorobenzene (ClB). The theoretical integral and differential cross sections (DCSs) were obtained with the Schwinger multichannel method implemented with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR). The calculations with the SMCPP method were done in the static-exchange (SE) approximation, for energies above 12 eV, and in the static-exchange plus polarization approximation, for energies up to 12 eV. The calculations with the IAM-SCAR method covered energies up to 500 eV. The experimental differential cross sections were obtained in the high resolution electron energy loss spectrometer VG-SEELS 400, in Lisbon, for electron energies from 8.0 eV to 50 eV and angular range from 7 degrees to 110 degrees. From the present theoretical integral cross section (ICS) we discuss the low-energy shape-resonances present in chlorobenzene and compare our computed resonance spectra with available electron transmission spectroscopy data present in the literature. Since there is no other work in the literature reporting differential cross sections for this molecule, we compare our theoretical and experimental DCSs with experimental data available for the parent molecule benzene. Published by AIP Publishing

Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

13 págs.; 7 figs.; 8 tabs.© 2015 AIP Publishing LLC. The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5-10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.F.F.S. and P.L.V. acknowledge the Portuguese Foundation for Science and Technology (FCT-MEC) through Grant Nos. SFRH/BPD/68979/2010 and SFRH/BSAB/105792/2014, respectively, the research Grant Nos. PTDC/FIS-ATO/1832/ 2012 and UID/FIS/00068/2013. P.L.V. also acknowledges his Visiting Research Fellow position at Flinders University, Adelaide, South Australia. The Patrimoine of the University of Liège, the Fonds National de la Recherche Scientifique, and the Fonds de la Recherche Fondamentale Collective of Belgium have also supported this research. E.L. and R.F.C.N. thank CNPq (Brazil) and the Science Without Borders Programme for opportunities to study abroad. The authors wish to acknowledge the beam time at the ISA synchrotron at Aarhus University, Denmark. The research leading to these results has received funding from the European Community’s Seventh Framework Programme (Grant No. FP7/2007-2013) CALIPSO under Grant Agreement No. 312284. D.B.J. thanks the Australian Research Council for financial support provided through a Discovery Early Career Research Award. M.J.B. also thanks the Australian Research Council for some financial support, while M.J.B. and M.C.A.L. acknowledge the Brazilian agencies CNPq and FAPEMIG for financial support. F.B. and G.G. acknowledge partial financial support from the Spanish Ministry MINECO (Project No. FIS2012-31230) and the EU COST Action No. CM1301 (CELINA). Finally, R.F.C., M.T.do N.V., M.H.F.B., and M.A.P.L. acknowledge support from the Brazilian agency CNPq.Peer Reviewe

Differential cross sections for electron impact excitation of the electronic bands of phenol

We report results from a joint theoretical and experimental investigation into electron scattering from the important organic species phenol (C6H5OH). Specifically, differential cross sections (DCSs) have been measured and calculated for the electron-impact excitation of the electronic states of C6H5OH. The measurements were carried out at energies in the range 15–40 eV, and for scattered-electron angles between 10° and 90°. The energy resolution of those experiments was typically ∼80 meV. Corresponding Schwinger multichannel method with pseudo-potentials calculations, with and without Born-closure, were also performed for a sub-set of the excited electronic-states that were accessed in the measurements. Those calculations were conducted at the static exchange plus polarisation (SEP)-level using a minimum orbital basis for single configuration interaction (MOBSCI) approach. Agreement between the measured and calculated DCSs was typically fair, although to obtain quantitative accord, the theory would need to incorporate even more channels into the MOBSCI

Elastic Differential Cross Sections for Electron Scattering with Dichloromethane

In the present study joint experimental and theoretical elastic differential cross sections for electron scattering from dichloromethane in the incident electron energy region 7 to 50eV are discussed

Elastic scattering of slow electrons by n-propanol and n-butanol

We report measured and calculated cross sections for elastic scattering of low-energy electrons by the alcohols n-propanol and n-butanol in the gas phase. The measurements were carried out using the relative-flow method with an aperture source rather than a conventional tube or capillary-array source, eliminating the need to know molecular diameters. The calculations employed two different implementations of the Schwinger multichannel variational method and included polarization effects. The differential cross sections are dominated by strong forward scattering due to the molecules' large electric dipole moments, but near 10 eV, they display structure at intermediate angles that is probably associated with shape resonances, notably a pronounced f-wave scattering pattern. Overall agreement between the measured and calculated results is fair. We compare the cross sections of these larger alcohols to those of methanol and ethanol, as well as to those of alkanes

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Combined experimental and theoretical study on the differential elastic scattering cross sections for acetone by electron impact energy of 7.0-50 eV

7 págs.; 3 figs.; 1 tab.We report elastic differential cross sections (DCSs) for electron interactions with acetone, C3H6O. The incident electron energy range was 7.0-50 eV, and the scattered electron angular range for the differential measurements varied from 10° to 120°. The calculated cross sections were obtained with two different methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP), and the independent-atom method with screening-corrected additivity rule (IAM-SCAR). The present elastic DCSs have been found to agree well with the results of IAM-SCAR calculations above 20 eV, and also with the SMC calculations below 30 eV. Although some discrepancies were found for lower energies, the agreement between the SMCPP data and the DCSs obtained with the IAM-SCAR method improves, as expected, as the impact energy increases. Comparison with previous DCSs shows good agreement albeit the present data is extended down to lower electron impact energies. We find a low-lying π∗ shape resonance located at 2.6 eV, in agreement with recent results on electron collisions with acetone [M. G. P. Homem et al., Phys. Rev. A 92, 032711 (2015)10.1103/PhysRevA.92.032711]. The presence of a σ∗ resonance is also discussed. ©2016 American Physical SocietyAcknowledge the Brazilian Agency Coordenacao de Aperfeicoamento de Pessoal de Nıvel Superior (CAPES), under CAPES/FCT Programme (Process No. 23038.002465/2014-87).E.L. acknowledges the Brazilian Agency Conselho Nacional de Desenvolvimento Cientıfico e Tecnologico (CNPq) and the Science Without Borders Programme for opportunities to study abroad. M.H.F.B. also acknowledges support from CNPq. F.F.S. acknowledges the Portuguese National Funding Agency FCT through Researcher Contract No. IF-FCT IF/00380/2014, and, together with P.L.V., Research GrantsNo. PTDC/FIS-ATO/1832/2012 and No. UID/FIS/00068/2013. This work has been partially supported by the Spanish MINECO(Project No. FIS2012-31230).We also acknowledge financial support from European Union programs (COST CM1301 and FP7-ITN ARGENT). This work was also supported by FCT-MCTES, Radiation Biology and Biophysics Doctoral Training Programme (RaBBiT, PD/00193/2012); UID/Multi/04378/2013 (UCIBIO).Peer Reviewe