Metallic cluster beams from a 2.5 MV Van de Graaff accelerator for cluster–solid interaction studies: preliminary results with Aun+ clusters

Abstract

A liquid metal ion source (LMIS) was installed on the high-voltage terminal of the 2.5 MV singlestage Van de Graaff accelerator of the Institut de Physique Nucléaire de Lyon and was used to deliver intense MeV energy beams of cluster ions. After acceleration, the ions produced from an eutectic Au-Si alloy were mass-selected by means of a magnetic analysis. The beam was mainly composed of the monoatomic ions Au + and Si + and of the clusters Au + n , AunSi + , and AunSi + 2 (n = 2 − 13). The intensities decreased for increasing n values, but remained remarkably high. For pure gold ions, the maximum intensity measured at the target site varied from 250 nA, for Au + , down to 20 pA, for Au + 9 . The research program on the study of the specific effects of the impact of energetic clusters on solid surfaces concerns the fundamental interaction processes and the solid modifications induced by high-density energy deposits. Our first experiments with Au + n clusters led to the following results: Nonlinear dependence on the cluster size of kinetic secondary electron emission from thin carbon foil enhances the damage rate of irradiated silicon crystals as compared to monoatomic Au + ion effects.PACS. 79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces -36.40.-c Atomic and molecular clusters -61.80.Lj Atom and molecule irradiation effects

The Aun cluster probe in secondary ion mass spectrometry: influence of the projectile size and energy on the desorption/ionization rate from biomolecular solids

“…For each value of n / q there is a certain mass and charge distribution. The large size clusters with n / q = 100 used in this work have an average charge of 4+ and an average number of constituents of 400 (quoted as Au 400 in the following). A LMIS connected to the Van De Graaf accelerator of the Institut de Physique Nucléaire of Lyon 25. In this instrument the minimum and maximum acceleration voltages are 150 kV and 2 MV, and the cluster mass is selected after acceleration by an analyzing magnet.…”

“…A LMIS connected to the Van De Graaf accelerator of the Institut de Physique Nucléaire of Lyon 25. In this instrument the minimum and maximum acceleration voltages are 150 kV and 2 MV, and the cluster mass is selected after acceleration by an analyzing magnet.…”

Very large gold and silver sputtering yields induced by keV to MeV energyAunclusters(n=1–13Bouneau1, Brunelle2, Della‐Negra3 et al. 2002Phys. Rev. BSelf Cite1457722View full textAdd to dashboardCite

“…This accelerator is equipped with a liquid metal ion source 5 installed in the high voltage terminal of the machine and produces beams of gold clusters accelerated to total energies from 300 keV to 1.4 MeV. 6 A magnet at the exit of the accelerator is used to select the chosen Au n + cluster, with n from 1 to 13. As the magnet deflects the heavy gold clusters at a very small angle only, a 6 m long beam tube has to be used to sufficiently separate the desired cluster from the others.…”