ENERGY-LOSS OF HYDROGEN PROJECTILES BELOW THE BOHR VELOCITY IN AMORPHOUS-CARBON

Electronic stopping cross section data of amorphous carbon for hydrogen projectiles with velocities from 0.35v(Bohr) to 0.63v(Bohr) are presented. Experiments were done on a set of thin self-supporting carbon foils, utilizing a time-of-flight apparatus. A procedure is used which avoids the main errors inherent to transmission experiments, e.g., that due to target inhomogeneity and that due to target surface contamination. Protons, deuterons and molecular projectiles were used. We find that incident H2+ and H3+ molecules experience a smaller energy loss than protons and deuterons of equal velocity.