A laboratory study of ion-induced erosion of ice-covered carbon grains

摘要: Context. It has been confirmed that solid carbon dioxide (CO2) is abundantly present along the line of sight to quiescent clouds and star-forming regions via space IR observations with ISO-SWS Spitzer Space Telescope. Since CO2 low abundance in gas-phase, assumption it synthesized on grains after energetic processing icy mantles surface reactions. Aims. The role investigated as a reservoir for molecule formation structural modifications material without an ice layer upon ion bombardment. Methods. A gas-phase condensation technique was used prepare 13 C amorphous grains. These were covered H2 Oa nd O 2 finally bombarded 200 keV protons. new molecular species analyzed using spectroscopy. cross sections CO determined from increase column density function fluence. In addition, bare comparable fluence protons study layer. Imaging techniques such transmission electron microscopy monitor changes structure. Results. formed efficiently at interface between expense carbon, leading strong grain erosion. Given initial thickness our C-samples (about 120 nm), this resulted erosion about 50% proton bombardment 6.76 × 10 16 ions/cm . follows exponential trend irradiation asymptotic values obtained when O2 deposited top are one order magnitude higher than H2O strongly graphitized Less graphitization accompanied by fullerene molecules structures cage fragments original observed beneath graphitic Conclusions. restricts lifetime may influence more complex astrophysical environments. Graphitization carbonaceous affect spectral properties particular far-IR range.