Using GCIB a surface is bombarded by a beam of high-energy, nanoscale cluster ions. The clusters are formed when a high pressure gas (approximately 10 atmospheres pressure) expands into a vacuum (1e-5 atmospheres). The gas expands adiabatically and cools then condenses into clusters. The clusters are nano-sized bits of crystalline matter with unique properties that are intermediate between the realms of atomic physics and those of solid state physics. The expansion takes place inside of a nozzle that shapes the gas flow and facilitates the formation of a jet of clusters. The jet of clusters passes through differential pumping apertures into a region of high vacuum (1e-8 atmospheres) where the clusters are ionized by collisions with energetic electrons. The ionized clusters are accelerated electrostatically to very high velocities, and they are focused into a tight beam.