Aromatic clusters coordination numbers, m_cluster (red lines, upper and lower limits shown dashed), and number of network linking bonds, n_link, in a-C(:H) nanoparticles as a function of N_R and radius (0.4, 0.6, 0.8, 1.0, 1.2 nm, thin to thick black and grey lines, respectively). For each particle radius (same line thickness) the blue cross ordinate indicates the size-dependent hydrogen to carbon atomic ratios, [H]/[C], multiplied by 10.