Electron-phonon coupling and the sensitivity of metals to irradiation with swift heavy ions

In the framework of the thermal spike model, the present paper shows a relationship between the behaviour of metals under irradiation with swift heavy ions and two main parameters: the electron-phonon coupling strength g and the energy Delta H necessary to melt the material. A correlation is made between the electronic stopping power threshold (S-eth) of track formation, the order of magnitude of the track radii, and the values of g and Delta H. Three cases are discussed: bismuth that shows large track radii and a rather high value of S-eth, titanium that exhibits low values of track radii and S-eth, and iron which is an intermediate case (low values of track radii and high value of S-eth). The correlation deduced from those cases is successfully applied to C-60 fullerene crystals.