A velocity map imaging spectrometer for measuring absolute differential cross sections for ion-induced electron emission from molecules

International audienceIn this paper, we present a newly developed crossed beam experimental setup that utilizes the velocity map imaging (VMI) technique to measure simultaneously both kinetic energy and emission angle of electrons emitted from atoms or molecules upon ion collision. The projectile ion beam with keV to MeV kinetic energy crosses orthogonally the neutral target beam produced by an effusion cell. The emitted electrons are extracted and analyzed by a multi-electrode VMI spectrometer. By monitoring the target density, the projectile ion beam intensity and the beams' overlap, we are able to measure absolute differential cross sections for collisioninduced electron emission from molecules. The characterization of the setup and the methodology will be presented as well as first results for electron emission from uracil upon 0.98-MeV/u $^{12}$C$^{4+}$ collision