标题： 两光子光谱在相反宇称态之间 显示英文标题

标题： Two-Photon Spectroscopy Between States of Opposite Parities

摘要： 磁偶极子和电偶极子双光子吸收(MED-TPA)，最近被引入作为一种新的光谱技术，用于研究奇偶性相反态之间的跃迁，从理论角度进行了研究。 一种称为{\it 弱拟闭包近似}的新近似方法与对称性适应技术一起被用来计算具有明确对称性质的状态之间的跃迁幅度。 推导了MED-TPA的选择规则，并与奇偶性禁戒的电偶极子双光子吸收(ED-TPA)的选择规则进行了比较。 显示英文摘要

摘要： Magnetic- and electric-dipole two-photon absorption (MED-TPA), recently introduced as a new spectroscopic technique for studying transitions between states of opposite parities, is investigated from a theoretical point of view. A new approximation, referred to as {\it weak quasi-closure approximation}, is used together with symmetry adaptation techniques to calculate the transition amplitude between states having well-defined symmetry properties. Selection rules for MED-TPA are derived and compared to selection rules for parity-forbidden electric-dipole two-photon absorption (ED-TPA).