Non-additive effects in secondary-ion emission from V, Nb and Ta under gold-cluster bombardment

Comparative studies of the emission of secondary cluster ions in sputtering of the V group metals (V, Nb, Ta) by Aum (m ¼ 1–9) molecular ions with energies of 6–21 keV have been carried out. For all the metals, a strong non-additive increase in the yield of the secondary ions under cluster bombardment is observed. The non-additivity coefficients Kmm0 increase with the raise of the number of atoms n in the sputtered cluster ions reaching the values of 70–150 for K31 with n ¼ 10–12. The raise in the yield of atomic Vþ, Nbþ, Taþ ions with quasi-thermal energy has been found with the increase in the number of atoms in the bombarding Aum ions. # 2004 Published by Elsevier B.V.