  Co-sputtered Au-Ni thin films having thickness of 30 nm were deposited on
Si(100) substrates and irradiated with 160 keV ^{40}Ar^{+} under ambient
condition at a number of fluences and analyzed using Rutherford backscattering
spectrometry (RBS). The variation of Au signal counts in the RBS spectra with
ion dose has been investigated. The distribution of Au, Ni and Si atoms over
various depths within the as deposited and irradiated samples have been
computed using the backscattering data by means of a direct analytical method.
Au and Si profiles have been fitted with error function and the relative
changes in variance for various ion fluences compared to that of as deposited
profiles have been studied. The spreading rates of different constituents
across the interface due to Ar ion impact have also been discussed.
