在小信号高分辩激光光谱中,当不同J态在超精细结构态F的混合可以忽略时,起源于同一个J能级的原子各个同位素总电偶极跃迁强度正比于它们的丰度。在一个F-F′跃迁内的强度分布可以用群论计算出来。用内调制激光光谱方法测量铀的实验证实了理论的结果。

The total electric-dipole transition intensity originated from the same J-manifold in the small signal high resolution laser spectroscopy between different isotopes of atoms is proportional to their abundance providing that J-mixing from different J states into a hyperfine structure F state is negligible. The intensity distribution of single F-F′ transition can be calculated from group theory. Experiments of uranium using intermodulated laser spectroscopy confirmed the theoretical prediction.