candidate: Moseley , after discussions with Bohr who was at the same lab ( and who had used Van den Broek 's hypothesis in his Bohr model of the atom ) , decided to test Van den Broek 's and Bohr 's hypothesis directly , by seeing if spectral lines emitted from excited atoms fitted the Bohr theory 's postulation that the frequency of the spectral lines be proportional to the square of " Z " .