摘要
It is shown that negative ions are ejected from gas-phase water molecules when bombarded with positive ions at keV energies typical of solar-wind velocities. This finding is relevant for studies of planetary and cometary atmospheres, as well as for radiolysis and radiobiology. Emission of both H- and heavier (O- and OH-) anions, with a larger yield for H-, was observed in 6.6-keV(16)O(+) + H2O collisions. The experimental setup allowed separate identification of anions formed in collisions with many-body dynamics from those created in hard, binary collisions. Most of the anions are emitted with low kinetic energy due to many-body processes. Model calculations show that both nucleus-nucleus interactions and electronic excitations contribute to the observed large anion emission yield.
- 出版日期2015-6-29
- 单位中国地震局