We could assume that the electron cloud density and its energy levels stay consistent but there will be an “Isotope” shift in the monopole and thus energy levels. If we assume that this shift is negligible then when we measure and calculate the a_1 of the isotope we can compare this to the a_1 of the original nucleus (a_0). C and B_J will be the same for both and thus we end up with a_1/a_0 = (meu_1*I_0)/(meu_0*I_1). We can isolate I_1 and find out what it is!