Inner shell excitation, valence excitation and core ionization in NF 3 studied by electron energy-loss and X-ray photoelectron spectroscopies

Abstract

Electron energy-loss Spectroscopy (EELS) at impact energies of 2.5–3 keV has been used to obtain the electron excitation spectra for the N 1 s ( K-shell), F 1 s ( K-shell) and valence shell regions of NF 3. The inner shell spectra were recorded using small angle scattering (⩽1° ) while the valence shell spectrum was obtained at zero degree scattering angle. The inner shell excitation spectra show a strongly enhanced 1 s→ δ * type transition and continuum features which are typical for molecules with highly electronegative ligands. One of the peaks in an earlier published photoabsorption study of the N 1 s region has been shown to be due to a N 2 impurity. The valence shell electron energy-loss spectrum shows a number of transitions which are considered to be mainly due to valence-valence type transitions, with also some evidence of Rydberg structure. The X-ray photoelectron spectra (XPS) of the N 1 s and F 1 s electrons along with their associated satellite structures have also been recorded using Al Kα (1486.58 eV) radiation. The vertical ionization potentials for the N 1 s and F 1 s electrons were found to be 414.36 (10) eV and 693.24 (10) eV, respectively. Both spectra exhibit a rich and different satellite structure. These “shake-up” features in the satellite XPS spectra are compared with continuum features of the inner shell electron energy-loss spectra and also with the valence shell spectrum.