a detailed analysis of the electron-impact-induced fragmentation of 5,8dithiaspiro (3.1) octane and s,9-dithiaspiro 6.5) nonane is presented. the tetradeuteri6-analog of the cyclic dithioketals is prepared as an aid in analysing the fragmentation patterns. it was readily seen that the nature of the fragmentation pathway was governed by the size of the ring containing the two sulfur atoms and th...