Internal Energy Distribution of Secondary Ions Under Argon and Bismuth Cluster Bombardments: “Soft” Versus “Hard” Desorption–Ionization Process

Tingting Fu (1, 2, 3) , Serge Della-Negra (1) , David Touboul (3) , Alain Brunelle (3)

1 UP11 - Université Paris-Sud - Paris 11
2 IPNO - Institut de Physique Nucléaire d'Orsay
3 ICSN - Institut de Chimie des Substances Naturelles

The emission/ionization process under massive argon cluster bombardment was investigated by measuring the internal energy distributions of a series of benzylpyridinium ions. Argon clusters with kinetic energies between 10 and 20keV and cluster sizes ranging from 500 to 10,000 were used to establish the influence of their size, energy, and velocity on the internal energy distribution of the secondary ions. It is shown that the internal energy distribution of secondary ions principally depends on the energy per atom or the velocity of the cluster ion beam (E/n v(2)). Under low energy per atom (E/n?10eV), the mean internal energy and fragmentation yield increase rapidly with the incident energy of individual constituents. Beyond 10eV/atom impact (up to 40eV/atom), the internal energy reaches a plateau and remains constant. Results were compared with those generated from bismuth cluster impacts for which the mean internal energies correspond well to the plateau values for argon clusters. However, a significant difference was found between argon and bismuth clusters concerning the damage or disappearance cross section. A 20 times smaller disappearance cross section was measured under 20keV Ar-2000(+) impact compared to 25keV Bi-5(+) bombardment, thus quantitatively showing the low damage effect of large argon clusters for almost the same molecular ion yield.

Domaines: Physique Générale [physics.gen-ph]

Tingting Fu, Serge Della-Negra, David Touboul, Alain Brunelle. Internal Energy Distribution of Secondary Ions Under Argon and Bismuth Cluster Bombardments: “Soft” Versus “Hard” Desorption–Ionization Process. J.Am.Soc.Mass.Spectrom., 2018, 30 (2), pp.321-328. ⟨10.1007/s13361-018-2090-z⟩. ⟨hal-02024237⟩