Existence of transient temperature spike induced by SHI: evidence by ion beam analysis

The passage of high-energy heavy ions (swift heavy ions or SHI) through insulators and certain other materials creates extensive defects along the ion path beyond certain threshold of electronic energy loss. Such columnar defects are explainable by Coulomb explosion or by thermal spike. We have carried out couple of experiments in oxide materials, fullerene thin films and metal systems, which give an indirect evidence of the existence of transient temperature spike. The on-line ERDA analysis is performed (i) to measure electronic sputtering of thin films by measuring the loss of material with the fluence and (ii) to quantify interface modification by quantifying the changes at the interface with fluence. The observations in electronic sputtering were qualitatively explainable by the thermal spike model. Interface modification was quantitatively explained to be due to the diffusion of species during the transient melt phase. The inputs about the diameter of columnar defect region and the duration of melt phase are taken from thermal spike model. Diffusivity so obtained in the measurements is in the range or 10(-8) to 10(-6) m(2) s(-1). Such a high diffusivity is possible only for the molten state. Thus the SHI induced phenomena at the surface and interface are explained qualitatively and quantitatively respectively, supporting the existence of transient temperature spike. (C) 2004 Elsevier B.V. All rights reserved.