A comparison is made of the profiles of lead and bismuth X-ray M-alpha and
M-beta characteristic lines for the cases of their emission by free atoms a
nd atoms in a solid. The maxima of the lines emitted by free atoms are shif
ted to the red by about Delta lambda/lambda similar or equal to 10(-4). The
free-atom line profiles exhibit a structure, which is not observed in emis
sion of a solid.