An inelastic threshold in electron - alkali cluster collisions

An analysis of integral cross sections for slow electron collisions with ne utral sodium clusters and nanoparticles reveals that, in addition to an eff ective negative ion formation channel, there exists a strong inelastic thre shold-type process which appears above a collision energy of 1-1.3 eV. We s how that it can be plausibly associated with the onset of direct electron-i nduced cluster fragmentation. This result highlights the importance, of und erstanding the dynamics of electron-vibrational energy transfer in nanoclus ters, including the relative probability of direct vs, statistical energy t ransfer.