Resonance in the electron impact excitation intensities of the inner-shell states of N2

Abstract

The design and performance of a new electron energy loss spectrometer capable of obtaining both valence and inner-shell spectra of simple molecules are discussed. Incorporated into the spectrometer are two hemispherical deflectors, for energy selection and analysis, three sets of electron optics, for electron focusing and transport, and an energy add-lens for energy loss selection. A computer model developed to simulate the trajectories of the electrons within the spectrometer is presented. Experimental measurements on electron beam profiles are compared to those predicted by the model. A shape resonance structure observed in the electron impact excitation of the inner-shell (1s)$\sp{-1}$ (2$p\pi$) $\sp{1.3}\Pi$ states of CO has been extended to N$\sb2$. Using incident electrons of low-energy we have observed a resonance structure in the excitation intensities of the inner-shell $(1s)\sp{-1}$ (2$p\pi$) $\sp{1.3}\Pi$ states of N$\sb2$. The ratio of these excitation intensities show a resonance structure for incident electron energies between 418 and 419 eV. This resonance which is about 17.5 eV above the excitation threshold of these states is the analogue of the shape resonance in NO, the equivalent core molecule of $N\sbsp{2}{K\sp\*}$.