原子核可以通过某种方式(譬如β衰变)达到激发态，处于激发态的原子核可以通过发射γ射线跃迁到低激发态或基态，这种现象称为γ衰变或称γ跃迁.核能级跃迁所发出的光子与原子能级跃迁所发出的光子没本质的差别，不同的是原子能级跃迁发射的光子能量只有eV~keV数量级，而核能级跃迁发射的光子能量却有MeV数量级.在不考虑核的反冲时，光子能量Eg可以表示为下面的形式Eg=Es-Ex.有时原子核从激发态到较低能态的跃迁并不放出光子，而是把能量直接交给核外电子，使电子脱离原子，这种现象称为内转换(IC)，脱离原子的电子称为内转换电子.处于激发态的原子核可以通过放射γ光子回到基态，也可以通过产生内转换电子回到基态，究竟发生的是哪种过程，完全决定于核的能级特性.内转换电子的动能与壳层电子的电离能之和应是原子核的两能级间的能量差.也就是等于在两原子核能级间跃迁所辐射出的γ光子的能量.对于内转换的研究是获得有关核能级知识的重要手段.当然通过内转换方式还可以产生原子的特征X射线.

Atomic nuclei can reach the excited state in some way (e.g. beta decay). Atomic nuclei in the excited state can transit to the low excited state or ground state by emitting gamma rays. This phenomenon is called gamma decay or gamma transition. There is no essential difference between photons emitted by nuclear level transition and photons emitted by atomic level transition. The difference is that the photon energy emitted by atomic level transition is only eV~ke. The photon energy emitted by the nuclear level transition is MeV. Without considering the recoil of the nucleus, the photon energy Eg can be expressed as Eg=Es-Ex. Sometimes the transition from the excited state to the lower energy state of the nucleus does not emit photons, but directly transfers the energy to the extranuclear electrons to make the electrons detach from the atom. This phenomenon is called internal conversion (IC), the zengyingji.37ix.com.cnslglj.37ix.com.cnzengsuji.37ix.com.cnzengsujisl.37ix.com.cnzengliang.37ix.com.cn

zhidaijil.37ix.com.cnelectrons detached from the atom. The nucleus in the excited state can return to the ground state either by radiating gamma photons or by producing the internally converted electrons. What exactly happens depends entirely on the energy level characteristics of the nucleus. The sum of the kinetic energy of the internally converted electrons and the ionization energy of the shell electrons corresponds to the energy difference between the two levels of the nucleus. That is to say, the energy difference between the two levels of the nucleus is equal to the energy difference between the two levels of the nucleus. The energy of gamma photons emitted by the transition. The study of internal conversion is an important means to acquire knowledge of nuclear energy levels. Of course, the characteristic X-ray of atoms can also be produced by internal conversion.