Cluster beams, nano-ripples, and bio applications

Gas cluster ions are aggregates of weakly bonded gas atoms or molecules. Upon the impact of an energetic gas cluster ion, multiple collisions occur between the target atoms and the atoms in the cluster ion. These impact processes are completely different from those of a collision-cascade process induced by a single atomic or molecular (monomer) ion. Although the impact process of gas cluster ions is different, ripples similar to those formed by monomer ions are formed by gas cluster ion impacts at oblique incidence. In this review, ripple formation by gas cluster ions is discussed with respect to their formation mechanism, characteristics, and applications as biosensors.