Agradecimentos: This work was funded through a collaborative program by the U.S. National Science Foundation under Grants No. PHY 0653452 and No. PHY 0653396 and by the Brazilian agency Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) under Project No. 490415/2007-5. R.F.d.C., M.H.F.B., M.C.A.L. and M.A.P.L. acknowledge additional support from CNPq and from the Brazilian agencies Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), the Paraná state agency Fundação Araucária, Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), and Financiadora de Estudos e Projetos (FINEP) under Project No. CT-Infra 1. M.H.F.B. further acknowledges computational support from Professor Carlos M. de Carvalho at DF-UFPR. Computational support from Centro de Computação John David Rogers (CCJDR) and from Centro Nacional de Processamento de Alto Desempenho em São Paulo (CENAPAD), where the calculations in Brazil were performed, is gratefully acknowledged Ver menos

Abstract: Experiments and ab initio calculations of the differential and integral cross sections for the electronic excitation from the ground state (1)A(1) to the B-3(2) and (3)A(1) states of gas-phase furan molecules by low-energy electron impact were performed. Experimental differential cross sections were measured at incident electron energies between 5 and 15 eV and for scattering angles from 10 degrees to 130 degrees. The calculated cross sections were obtained using the Schwinger multichannel method implemented with pseudopotentials. The influence of channel-coupling and polarization effects is investigated through the comparison between three different models of scattering calculations, each one considering a distinct channel-coupling scheme. The comparison of experimental and calculated cross sections for electronically inelastic electron scattering by C4H4O molecules is found to be mostly reasonable. The existing discrepancies in this combined theoretical and experimental study help to illustrate difficulties in readily establishing reliable electronic excitation cross sections of polyatomic molecules by low-energy electrons Ver menos