Microclusters from different structures of silicon and carbon are studied by SIMS under UHV conditions in the mass range below M = 200. The sputtered mass spectra of ions ${\text{Si}}_{\text{n}}^{+}$, ${\text{C}}_{\text{n}}^{+}$ and C_n were obtained from the 10 keV ${\mathrm{O}}_2^{+}$ primary beam bombardment. Comparisons of each spectrum in each group have shown the strong structure effects on the cluster patterns. A brief discussion on the results has been given.