Recently I synthesized a material. To specify, I loaded about 0.2%Mg on the synthesized MnO2 nanoparticles, the catalytic performance is very good. I guess that the trace amount of Mg may exist as the single-atom state on the surfaces of MnO2, but I don't know how to chatacterize the Mg. Usually in the publiactions, "heavy" metals such as Pt, Au or Ir acting as single atom catalysts will deposite on "light" supporting materials such as carbon, MOF, Al2O3 or TiO2. And STEM-HAADF will always be used to characterize these single atoms because it can detect and distinguish different elements with big difference in atomic numbers. However, in my research, the single atom Mg (I guess) is lighter than Mn, so STEM-HAADF does not work here. Can anyone give suggestions here? Thanks