Excitation and ionization states of ions penetrating solids

The nature of the states of the penetrating ion in dense media has been a subject of conjecture for some time. Until recently the only information available has been that obtained from (1) measurement of charge state distributions of ions after emergence from the target and (2) that adduced from measurement of the electronic stopping power of the ion. More information on stopping power has come from the use of the channeling technique. Measurements of X-ray production cross sections and X-ray energies generated in solids coupled with new knowledge concerning these processes have added to the picture. An overview of the subject including some recent experimental results is presented. (Auth.)