Sequential nonadiabatic excitation of large molecules and ions driven by strong laser fields
Sequential nonadiabatic excitation of large molecules and ions driven by strong laser fields
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DOI：
10.1103/physreva.69.013401
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发表时间：
2004-01-01
影响因子：
2.9
通讯作者：
Levis, RJ
中科院分区：
文献类型：
--
作者：
Markevitch, AN;Romanov, DA;Levis, RJ
从实验、理论和数值计算三个方面研究了强激光场中多原子分子离解电离的电子过程。使用飞行时间离子质谱，我们研究了一系列相关分子的激光强度上的碎片的依赖性，并报告了这种依赖于分子的大小，对称性和电子结构的规律性趋势。在此基础上，我们建立了强激光场中多原子分子的离解电离模型。该模型是建立在三个要素：（一）非绝热的人口转移从基态电子态的激发态歧管通过门口（电荷转移）过渡;（二）指数增强这种过渡的集体动态极化的所有电子，和（iii）连续的能量沉积在中性分子和由此产生的分子离子。连续的非绝热激发加速了一个大分子的极化率在其电离后的反直觉的增加。序列非绝热激发的一般理论构成了定量描述强激光场中多原子分子和离子中各种非线性过程的基础。
Electronic processes leading to dissociative ionization of polyatomic molecules in strong laser fields are investigated experimentally, theoretically, and numerically. Using time-of-flight ion mass spectroscopy, we study the dependence of fragmentation on laser intensity for a series of related molecules and report regular trends in this dependence on the size, symmetry, and electronic structure of a molecule. Based on these data, we develop a model of dissociative ionization of polyatomic molecules in intense laser fields. The model is built on three elements: (i) nonadiabatic population transfer from the ground electronic state to the excited-state manifold via a doorway (charge-transfer) transition; (ii) exponential enhancement of this transition by collective dynamic polarization of all electrons, and (iii) sequential energy deposition in both neutral molecules and resulting molecular ions. The sequential nonadiabatic excitation is accelerated by a counterintuitive increase of a large molecule's polarizability following its ionization. The generic theory of sequential nonadiabatic excitation forms a basis for quantitative description of various nonlinear processes in polyatomic molecules and ions in strong laser fields.