(γ, 2γ) experiments for studying the multiply excited states of N2

Full text:The dynamics and spectroscopy of multiply excited molecules are subjects of current interest because of the breakdown of the independent electron model and Born-Oppenheimer approximation. We propose an idea of the (γ, 2γ) experiments to observe the multiply excited molecules, apart from the contribution of the ionization: the two VUV photons emitted by fragment atoms produced from the multiply excited molecules are detected in coincidence with each other to eliminate the contribution from ionization processes. In this report, we present the results of the (γ, 2γ) experiments for studying the multiply excited states of N2 producing two fluorescent nitrogen atoms. The relative values of the doubly differential cross sections for the simultaneous emission of hv' and hv' in the process (1), d2 σ/dΩ1dΩ2 were measured as a function of hv. The relative values of the singly differential cross sections for the emission of atomic fluorescences, dσ'/dΩ, were also measured. The σ'/dΩ, curve (figure 1(a)) is dominated by the dissociative directionization with excitation leading to the emission of atomic fluorescences. On the other hand, the d2σ/Ω1dΩ2 curve is attributed to the process (1), and thus it follows that unknown multiply excited states of N2 above about 40 eV have been observed