  We use atomic spectra to extend pure Coulomb's law tests to larger masses. We
interpret these results in terms of constraints for hidden sector photons. With
existing data the bounds for hidden photons are not improved. However we find
that our atomic spectra bounds are an especially clean and model-independent
complement to existing ones from other methods. We also show that data from
future tests of true muonium and muonic atoms could produce atomic spectra
bounds which probe untested parameter space.
