Generalized oscillator strength for the 1B 2u← 1A g transition and the observation of forbidden processes at the C 1s spectrum of the naphthalene molecule

Abstract

The angular dependence of the valence and carbon 1s excitation in the naphthalene molecule has been studied using the electron energy-loss technique. The valence shell spectra were measured at 1.0 keV incident energy, 0–50 eV excitation energy range and in the 1.25–12.0 degrees angular range. The energy resolution was 1.0 eV (full-width at half-maximum (FWHM)). Absolute values were determined, for the first time, for the elastic differential cross section and for the generalized oscillator strength (GOS) and inelastic differential cross section for the 1B 2u← 1A g transition (5.9 eV). The carbon 1s spectrum (270–330 eV) was also measured, at 1.3 keV and at an energy resolution of approximately 1.0 eV (FWHM). Dipole-forbidden processes have been observed, both at the valence and C 1s excitation spectra. In the latter case, a previously unreported, dipole forbidden transition, has been observed at 290.3 eV.