The controlled growth of organic layer on surface is still awaiting for an on-line reliable monitoring that would allow improvement of its quality. We show here that the self-assembly of the perylene monolayer deposited on Ag(110) at room temperature can be tracked with low energy atoms in a regime where the energy perpendicular to the layer is less than 0.1 eV preventing damage to the layer. The image processing required for this triangulation technique with atoms is described in details.
