Abstract : The gamma observation of novae explosions is a one of the objectives of space telescopes like INTEGRAL. According to astrophysical models, the most intense ray of the gamma spectra of these phenomena has an energy of 511 keV. This ray is mainly due to the annihilation of ß+ coming from 18F decay. The astrophysical interpretation of the gamma observations can be done only if the nucleosynthesis of 18F is well understood. Actually, poor knowledge of the rate of the 18F(p,a)15O reaction, linked to the structure of the compound nucleus 19Ne, creates an uncertainty factor of 300 on the abundance of 18F in novae. In order to reduce these uncertainties, an inelastic scaterring experiment 19Ne(p,p')19Ne* was performed to the Louvain la Neuve laboratory. It allowed us to study excited states of 19Ne above alpha (3.55 MeV) and proton (6.42 MeV) thresholds. The study of angular correlation of particules decay (proton or alpha) was used to assign for the first time the spin of many known levels. In addition, a new large ½+ state, which could influence strongly the astrophysical factor, was observed for the first time.