Ionization of uracil in collisions with fast bare ions

We study the atomic collisions with large molecules and simple atoms. The ionization and fragmentation spectra are investigated for uracil, a RNA base molecule, under the impact of fast bare C, O and F-ions. The experiments are conducted using a recoil-ion time-of-flight spectrometer. The energy dependence of the total ionization cross sections (TCS) and fragmentation yields are measured for MeV/u energies. In addition, the angular distribution of the electron double differential cross sections (DDCS) are also shown in some cases. The total cross sections of ionization and also the DDCS data are compared with the CDW-EIS calculations. The qualitative agreement is good but, in general, the theory tends to overestimate the data by a factor of 2.2. The angular distribution of electrons clearly indicates a good qualitative agreement except for the lowest energy electrons

Doubly differential distribution of electron emission in ionization of uracil in collisions with 3.5-MeV/u bare C ions

We report the energy and angular distribution of the electron emission from an RNA base molecule uracil in collisions with 3.5-MeV/u bare C ions. The absolute double differential cross sections (DDCS) are measured for emission energy between a few to 600 eV. The angular distributions are compared to those obtained for the O2 molecule in the same experiment. The single differential cross sections (SDCS) are also deduced. The energy and angular distributions of the DDCS and SDCS are compared with the state-of-the-art quantum-mechanical models based on continuum distorted wave-eikonal initial state (CDW-EIS) and correct boundary first Born (CB1) approximations which use a suitable molecular wave function for uracil. The models, however, give substantial deviations from the observed energy and angular distributions of the DDCS as well as SDCS. The CDW-EIS calculations are closer to the data compared to the CB1. In the case of uracil a large difference in the forward-backward emission of electrons was observed in comparison to that in collisions with an oxygen molecule

Unexplained dissociation pathways of two-body fragmentation of methane dication

International audienc

Sputtering of sodium and potassium from nepheline: Secondary ion yields and velocity spectra

International audienc

Ion induced fragmentation of diatomic molecular clusters

International audienceWeakly bound atomic or molecular clusters are of growing interest in the fields of atmospheric science, hadron-therapy or astrophysics. We will present our recent experimental results on the fragmentation of diatomic molecular dimers after irradiation by highly charged ions. For (N2)2 dimers, the measured KER spectrum is very similar to the one of the N2 monomers but is globally shifted towards higher energies. Moreover, sequential dissociation of the (CO)2 dimers has been observed when metastable states of the CO2+ dications are populate