Observation of interference effects in the Moessbauer absorption spectra of E2 and E2/M1 transitions

In a transmission geometry, dispersion terms were observed in the shapes of the M\"ossbauer resonance lines of pure E2 and mixed E2/M1 transitions. For the pure E2 transitions studied, the relative magnitude of these terms, which are attributable to interference effects, is typically 1.5% of the depth of the absorption line. We discuss possible consequences of the resulting asymmetric line shape for isomer-shift measurements.