An improved analysis of Doppler-shifted γ spectra is outlined. This analysis is exact within the Lindhard theory of slowing down of heavy ions in solids.With an approximate cross section applicable at low energies, the equations become independent of the energy, except as a scaling parameter, and depend only on the projectile–target mass ratio. A set of universal curves of the mean fractional shift F(τ) is calculated in this approximation for several values of the mass ratio.Une analyse améliorée de spectres γ déplacés par effet Doppler est esquissée. Cette analyse est conforme à la théorie de Lindhard sur le ralentissement des ions lourds dans les solides.