Electronic sputtering of solid N2 by swift ions

Most sputtering yield measurements for solid N-2 are reported for stopping powers lower than 10(-13) eV cm(2)/molecule. We measured the sputtering yield for solid N-2 at stopping powers, in the electronic regime, above 10(-12) eV cm(2)/molecule, extending the range of such measurements by more than an order of magnitude, using a 33 (MeVNi9+)-Ni-58 swift heavy ions beam. The evolution of the thin N-2 ice films was monitored in-situ by mid-infrared spectroscopy (FTIR) during irradiation. As N-2 is only weakly infrared active, and can be hardly monitored directly via an infrared absorption mode in such experiments, we use the Fabry-Perot interference fringes of the ice film to evaluate, via an optical model, the erosion of the N-2 film as a function of ion fluence. A sputtering model including several sputtering crater shapes is developed and tested against experimental data. We derive the sputtering yield for a semi-infinite N-2 ice film and its dependence with the ice thickness for thin film conditions, monitoring the N-2 ice sputtering depth. We combine the results with previous measurements at lower stopping powers to derive the electronic sputtering of solid N-2 over a large stopping power range.