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X-ray emission of the nitrogen molecule following photon or electron impact. A theoretical study using configuration-interaction wavefunctions

1984; Elsevier BV; Volume: 83; Issue: 1-2 Linguagem: Inglês

10.1016/0301-0104(84)85219-2

1873-4421

Hans Ågren, Reidar Arneberg, Jiri Müller, Rolf Manne,

Advanced Chemical Physics Studies

Soft X-ray emission from gas-phase N2 molecules is calculated as dipole transitions in neutral, singly and doubly ionized molecules. The role of electron correlation for the initial-state creation and for the de-excitation with X-ray emission is investigated, i.e. for processes of resonance core-electron excitation in the neutral molecule, for shake-up and shake-off processes leading to singly and doubly ionized states, respectively, as well as for radiative electron rearrangement (RER) in the emission. A total theoretical X-ray emission spectrum of the N2 molecule is constructed from ab initio configuration-interaction wavefunctions and is compared with the available experimental spectrum. Transition moments are evaluated in the dipole-length form between non-orthogonal sets of molecular orbitals. The multiply bonded character of N2 and its low-lying 1πg orbital give rise to strong resonance transitions, strong transitions from multiply excited initial shake-up states and lead to a break-down of the MO picture in a large interval of the spectrum from doubly excited states. Significant RER transitions are predicted and compared with corresponding structures in the photoelectron spectrum.