INVESTIGATION OF THE VALENCE ELECTRONIC-STRUCTURE OF N-BUTANE USING (E,2E) SPECTROSCOPY

The first complete (e, 2e) measurements of the valence ionization spec trum (6-56 eV) of n-butane (C4H10) are reported for two relative azimu th angles. Measurements have been carried out using a high-resolution (Delta E = 0.9 eV, Delta p = 0.1 a.u.) spectrometer, using an impact e nergy of 1200 eV and symmetric non-coplanar kinematics. The results co nfirm a complete breakdown of the orbital picture of ionization of the innermost C-2s level, as predicted recently by a third-order ADC Gree n's function calculation. They also point out a strong angular depende nce of the relative intensities from which orbital symmetries can easi ly be traced. (C) 1998 Elsevier Science B.V. All rights reserved.