Dissociation and fragmentation of furan by electron impact

Dissociation and fragmentation processes that produce electronically excited atomic and molecular fragments, following electron impact excitation, have been studied in furan. The optical excitation technique has been employed over the electron incident energy range 15-95 eV. Formation of excited hydrogen atoms H(n) in the n = 4-10 states has been detected by observation of the Balmer series. The diatomic CH fragments are formed in the A(2)Delta, B-2 Sigma(-) and C-2 Sigma(-) electronic states and the C-2 fragments in the d(3)Pi(g) excited state. The appearance energies for the H(n = 4) (Hp line) and the CH(A(2)Delta) (A(2)Delta -> X-2 Pi(r) transition) fragments have been measured to be 20.7 +/- 0.4 and 19.0 +/- 0.3 eV, respectively. Absolute emission cross sections have been also determined for the above two transitions in the electron energy range from the appearance energy thresholds up to 95 eV. Possible dissociation and fragmentation processes are discussed. (C) 2008 Elsevier B.V. All rights reserved.