Non-Adiabatic Atomic Transitions: Computational Cross Section Calculations of Alkali Metal-Noble Gas Collisions
Non-Adiabatic Atomic Transitions: Computational Cross Section Calculations of Alkali Metal-Noble Gas Collisions
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发表时间：
2011-09
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通讯作者：
Charlton D. Lewis
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作者：
Charlton D. Lewis
翻译后摘要：二极管泵浦碱激光器的操作通过激发碱金属的气态电池的P（3/2）激发能态。电池中存在的惰性气体使碱金属碰撞去激发到其P（1/2）态。然后碱金属原子通过发射光子弛豫到它们的S（1/2）基态。由于惰性气体原子的非辐射去激发代表了DPAL操作的一个有趣的接合点。这个过程必须快于辐射弛豫回到S（1/2）状态的激光发生。非辐射退激发的速率与碰撞截面有关，而碰撞截面与S矩阵有关。本文提出了一种与时间相关的计算方法--通道包法，用于计算碱金属-惰性气体碰撞的S矩阵元。S-矩阵包含MNg系统在体固坐标系中的密耦哈密顿量，该密耦哈密顿量表示在状态的P-流形中。多重态内混合主要有两种态-态耦合现象：自旋-轨道耦合和科里奥利耦合。在钾、铷和铯与惰性气体氦、氖和氩之间总共进行了九次碰撞的计算机模拟。计算了P（1/2）到P（3/2）转变的温度平均截面，并与实验进行了比较。
Abstract : Diode Pumped Alkali Lasers operate by exciting a gaseous cell of alkali metal to its P(3/2) excited energy state. A noble gas, present in the cell, collisionally de-excites the alkali metal to its P(1/2) state. The alkali atoms then relax to their S(1/2) ground state by emitting photons. The non-radiative de-excitation due to inert gas atoms represents an interesting juncture for DPALs operation. This process must be faster than the radiative relaxation back to the S(1/2) state for lasing to occur. The rate of non-radiative de-excitation is related to the collisional cross section and the cross section is related to the S-Matrix. A time-dependent algorithm, the Channel Packet Method, was implemented to predict S-Matrix elements for alkali metal - noble gas (MNg) collisions. The S-Matrix contains the close-coupled Hamiltonian of the MNg system in body-fixed coordinates represented in the P-Manifold of states. There were two major state-to-state coupling phenomena responsible for intramultiplet mixing: spin-orbit and Coriolis. A total of nine collisions were computationally simulated between Potassium, Rubidium, and Cesium and the noble gases Helium, Neon, and Argon. Temperature averaged cross-sections were calculated for the P(1/2) to P(3/2) transition and compared to experiment.