Isothermal electron beam heating has been used to anneal ion‐implanted silicon samples and the changes in the spectral &Vegr;(&lgr;,T) and total hemispherical &Vegr;Tot(T) emissivities caused by damage annealing and dopant activation have been monitoredinsitu. Free carrier absorption effects have been observed after annealing of a B‐implanted sample, resulting in an increase of &Vegr;(&lgr;,T) in the semitransparent region and an increase of &Vegr;Tot(T). An increase of normalized emissivity at 800 °C was also observed. ©1995 American Institute of Physics.