Nonlinear Atomic Response to Intense Ultrashort X Rays
Nonlinear Atomic Response to Intense Ultrashort X Rays
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DOI：
10.1103/physrevlett.106.083002
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发表时间：
2011-02-24
影响因子：
8.6
通讯作者：
DiMauro, L. F.
中科院分区：
文献类型：
--
作者：
Doumy, G.;Roedig, C.;DiMauro, L. F.
研究了氖原子对飞秒千伏级强x射线的非线性吸收机制。在低于Ne（8+），1s（2）吸收限的X射线频率下观察到Ne（9+）的产生，并表明与能量密度有明显的二次依赖关系。理论分析表明，该过程是Ne（8+）基态的双光子电离和瞬态激发态的单光子产生和电离的高阶序列过程的结合，其时间尺度快于Auger衰变。我们发现，非线性直接双光子电离截面的数量级高于预期从以前的计算。
The nonlinear absorption mechanisms of neon atoms to intense, femtosecond kilovolt x rays are investigated. The production of Ne(9+) is observed at x-ray frequencies below the Ne(8+), 1s(2) absorption edge and demonstrates a clear quadratic dependence on fluence. Theoretical analysis shows that the production is a combination of the two-photon ionization of Ne(8+) ground state and a high-order sequential process involving single-photon production and ionization of transient excited states on a time scale faster than the Auger decay. We find that the nonlinear direct two-photon ionization cross section is orders of magnitude higher than expected from previous calculations.