Intense and purified radioactive beam of post-accelerated 14 O was used to study the low-lying states in the unbound 15 F nucleus. Exploiting resonant elastic scattering in inverse kinematics with a thick target, the second excited state, a resonance at E R =4.757(6)(10) MeV with a width of Γ=36(5)(14) keV was measured for the first time with high precision. The structure of this narrow above-barrier state in a nucleus located two neutrons beyond the proton drip line was investigated using the Gamow Shell Model in the coupled channel representation with a 12 C core and three valence protons. It is found that it is an almost pure wave function of two quasi-bound protons in the 2s 1/2 shell.

γ-ray production cross sections have been measured in proton irradiations of N, Ne and Si and α-particle irradiations of N and Ne. In the same experiment we extracted also line shapes for strong γ-ray lines of 16 O produced in proton and α-particle irradiations of O. For the measurements gas targets were used for N, O and Ne and a thick foil was used for Si. All targets were of natural isotopic composition. Beams in the energy range up to 26 MeV for protons and 39 MeV for α-particles have been delivered by the IPN-Orsay tandem accelerator. The γ rays have been detected with four HP-Ge detectors in the angular range 30 • to 135 • . We extracted 36 cross section excitation functions for proton reactions and 14 for α-particle reactions. For the majority of the excitation functions no other data exist to our knowledge. Where comparison with existing data was possible usually a very good agreement was found. It is shown that these data are very interesting for constraining nuclear reaction models. In particular the agreement of cross section calculations in the nuclear reaction code TALYS with the measured data could be improved by adjusting the coupling schemes of collective levels in the target nuclei 14 N, 20,22 Ne and 28 Si. The importance of these results for the modeling of nuclear γ-ray line emission in astrophysical sites is discussed.