  High-kinetic energy impacts between inorganic surfaces and molecular beams
seeded by organics represent a fundamental case study in materials science,
most notably when they activate chemical-physical processes leading to
nanocrystals growth. Here we demonstrate single-layer graphene synthesis on
copper by C60 supersonic molecular beam (SuMBE) epitaxy at 645 {\deg}C, with
the possibility of further reduction. Using a variety of electron spectroscopy
and microscopy techniques, and first-principles simulations, we describe the
chemical-physical mechanisms activated by SuMBE resulting in graphene growth.
In particular, we find a crucial role of high-kinetic energy deposition in
enhancing the organic/inorganic interface interaction, to control the cage
openings and to improve the growing film quality. These results, while
discussed in the specific case of graphene on copper, are potentially
extendable to different metallic or semiconductor substrates and where lower
processing temperature is desirable.
