Outer-valence ionization of nitrous oxide: A high-resolution electron momentum spectroscopy investigation

We report a detailed study on the outer-valence ionization of nitrous oxide (N2O) by a high-resolution (e, 2e) spectrometer employing asymmetric non-coplanar kinematics at an impact energy of 2500 eV. Binding energy spectrum in the energy region of 11–30 eV is obtained. Benefiting from the high energy resolution of 0.55 eV, four main peaks and six satellite structures are clearly identified in this region. The measured electron momentum profiles are compared with the theoretical calculations. Renner-Teller-effect induced geometry distortion is used to qualitatively interpret the observed discrepancy at low momentum between experiment and theory for B2Π state. The assignments and the pole strengths for these ionization states are determined by comparing the shape and the intensity of the experimental electron momentum profiles with those of the theoretical ones. In particular, two low-lying satellites at 21.0 eV and 27.1 eV are confirmed for the first time and attributed to the 2Π and 2Σ shake-up states. The present results show the evidence of strong electron correlation effects in the final states for the outer-valence ionization of N2O.