Secondary ion emission from niobium and tantalum

Summary form only given, as follows. Summary form only given. The comparative study of mass-spectra, relative yields and kinetic energy distribution of Nb and Ta atomic and cluster ion sputtered from niobium and tantalum surfaces by atomic and polyatomic Au/sup $/projectiles has been carried out. The essential increase of the contribution of polyatomic clusters to the total yield of sputtered charged particles is observed at the transition from atomic ion bombardment to polyatomic one. The large cluster ions sputtered by polyatomic ion bombardment have higher kinetic and vibration energies than those produced by the atomic ion bombardment with the same energy per atom.