The chemical effect of Hg, Pb and Bi compounds on the average L shell fluor
escence yields (<(omega)over bar>(L)) was investigated. The samples were ex
cited by gamma-rays 59,5 keV in energy produced by a Am-241 radioisotope so
urce. The L X-rays emitted by the samples were counted using a Si(Li) detec
tor with a resolution of 160 eV at 5.9 keV. The chemical effects of Hg, Pb
and Bi compounds which we have observed on the average L shell fluorescence
yield (<(omega)over bar>(L)) were compared with theoretical values.