论文标题
直接两光子电离中库珀最小值的电偶极子近似的分解
Breakdown of the electric dipole approximation at Cooper minima in direct two-photon ionisation
论文作者
论文摘要
我们预测，在直接两光子$ k- $ shell原子原子电离中通过圆极化的光在非线性库珀最小值下的电偶极近似值的分解。根据基于电偶极近似的预测，我们希望将入射光子能调整为两光子离子化的库珀最小值，从而导致最初结合的$ 1S $电子的一个自旋预测纯粹耗尽，因此将电离原子留在一个方向的状态下。我们表明，通过包括电四极相互作用，可以获得显着的方向纯度。剩余的离子取向的低度可直接访问原子和分子的两光子电离中电偶极子近似之外的电子 - 光子相互作用的贡献。可以直接通过船尾分析仪或随后的$Kα$荧光发射来直接检测照片的方向，该荧光发射的信息具有有关发射光子极化的离子方向的信息。
We predict breakdown of the electric dipole approximation at nonlinear Cooper minimum in direct two-photon $K-$shell atomic ionisation by circularly polarised light. According to predictions based on the electric dipole approximation, we expect that tuning the incident photon energy to the Cooper minimum in two-photon ionisation results in pure depletion of one spin projection of the initially bound $1s$ electrons, and hence, leaves the ionised atom in a fully oriented state. We show that by inclusion of electric quadrupole interaction, dramatic drop of orientation purity is obtained. The low degree of the remaining ion orientation provides a direct access to contributions of the electron-photon interaction beyond the electric dipole approximation in the two-photon ionisation of atoms and molecules. The orientation of the photoions can be experimentally detected either directly by a Stern-Gerlach analyzer, or by means of subsequent $Kα$ fluorescence emission, which has the information about the ion orientation imprinted in the polarisation of the emitted photons.
