The local vibrational densities of states of highly dilute Fe (0.017 at. %)
in Al metal and Fe (0.1 at. %) in Cu metal were measured by using nuclear
resonant inelastic scattering of synchrotron radiation. The characteristic
vibrational modes of Fe in Al were found to be modes of resonance with the
host Al phonon spectrum. In the measured spectrum of Fe in Cu, in addition
to resonance vibrational modes, just above the phonon cutoff energy of Cu m
etal a peak interpreted as being a localized mode predicted theoretically b
y the Green's-function method was found.