Surface emission studies of ion-beam bombarded thin melamine coatings on carbon substrates

Abstract

The knowledge of nitrogen content evolution in organic targets, as a function of beam fluence and surface roughness, is crucial in several research and applied fields. We investigated the degradation of melamine (C${}_3$H${}_6$N${}_6$) coatings, deposited on very thin carbon layers, under ion-beam bombardment at high-power density ($\approx 150{\mathrm{W/m}}^2$). Two types of effects due to the ionic collisions are observed: a prompt ejection of nitrogen atoms, occurring at a low particle fluence, and a subsequent, much slower, release of nitrogen, leading to a saturation-like effect. A detailed analysis of several long-lasting measurements with different layers revealed interesting inverse correlations between the yields of nitrogen ejections and the particle flux. Further, the damage cross section of melamine, leading to nitrogen emission during the slow phase, seems strongly connected to the surface roughness of the carbon backing used to host the melamine material.