Eur. Phys. J. D (2014) 68: 185
https://doi.org/10.1140/epjd/e2014-40811-6

Regular Article

Strong perturbation effects in heavy ion induced electronic sputtering of lithium fluoride

¹ Centre de Recherche sur les Ions, les Matériaux et la Photonique (CEA-CNRS-ENSICAEN-Université de Caen-Basse Normandie UCBN), CIMAP-CIRIL-GANIL, BP 5133, Boulevard Henri Becquerel, 14070 Caen Cedex 05, France
² Physics Department, Universidade Federal de Santa Catarina, 88000 Florianópolis, Brazil
³ Physics Department, Pontifícia Universidade Católica do Rio de Janeiro PUC, Rua Marquês de São Vicente 225, Gávea, 22453-900 Rio de Janeiro, Brazil

^a e-mail: rothard@ganil.fr

Received: 18 December 2013
Received in final form: 11 April 2014
Published online: 3 July 2014

Abstract

Electronic sputtering of lithium fluoride by swift heavy ions was studied as a function of electronic energy loss (dE/dx)_e. The single crystal targets were irradiated with swift heavy ion beams (166Z_P692; 46E_P/M_P (MeV/u) 611). This allowed varying the deposited energy by a factor of 20 (1.86dE/dx (keV/nm) 632). The sputtered secondary ions were measured from well controlled LiF targets without surface contaminations, by means of the time-of-flight technique (TOF-SIMS). The mass spectrum reveals an important contribution of clusters (over single ions), which increases with (dE/dx)_e. Another observation for the strongest perturbation at high dE/dx (>8 keV/nm) is that the secondary ion yields saturate: Y(dE/dx) = constant. In contrast, at lower dE/dx (<8 keV/nm) for weaker perturbation, the yield Y scales with (dE/dx)². This quadratic increase would rather point towards a thermal evaporation-like mechanism leading to electronic sputtering, however, the origin of the yield saturation remains an open finding.