Pendular alignment and strong chemical binding are induced in helium dimer molecules by intense laser fields
Pendular alignment and strong chemical binding are induced in helium dimer molecules by intense laser fields
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强激光场在氦二聚体分子中诱导摆动排列和强化学结合
DOI：
10.1073/pnas.1810102115
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发表时间：
2018-09
影响因子：
11.1
通讯作者：
Herschbach Dudley
中科院分区：
文献类型：
--
作者：
Wei Qi;Kais Sabre;Yasuike Tomokazu;Herschbach Dudley
重要意义脉冲激光提供的强电场可以深刻改变原子和分子的电子结构。对于氦二聚体，我们在两个领域开展了激光相互作用的理论研究：(I)不足以驱逐电子，但与各向异性极化率相互作用以诱导分子轴空间排列的场；(Ii)超强高频激光，促使电子经历与本征库仑力相互作用的颤动，并诱导极强的化学键。通过在II中包含一个激发电子态，我们带来了实验观察所缺乏的特征。强脉冲激光场提供了诱导分子空间排列和增强化学键强度的方法。激光场的持续时间通常从数百皮秒到几飞秒不等。因此，诱导的“激光修饰”性质可以是绝热的，只存在于脉冲期间，或非绝热的，持续到随后的无场区域。我们通过处理氦二聚体的基态(X1Σg+)和第一激发态(A1Σu+)来举例说明这些方面。基态二聚体在无场时几乎不受束缚，因此对电场非常敏感。我们考察了两个激光领域，分别被命名为(I)“侵入性”和(Ii)“驱动性”。我使用了强烈的非共振激光场，强度不足以驱散电子，但与二聚体的极化率相互作用，以诱导束缚态和摆动态，在这些态中，二聚体轴围绕电场方向摆动。II采用超强高频场，促使电子经历颤动，与本征库仑力相互作用，形成有效的结合势。然后，二聚体的键变得更加牢固。对于I，我们将激光诱导的摆动排列映射到X态，这对于无场二聚体是不存在的。对于II，我们评估了从X态到A态的振动跃迁，这是由颤动振荡的幅度决定的。
Significance Intense electric fields, provided by pulsed lasers, can profoundly alter the electronic structure of atoms and molecules. For the helium dimer, we carry out a theoretical study of laser interactions in two realms: (I) fields not strong enough to dislodge electrons, but interact with the anisotropic polarizability to induce spatial alignment of the molecular axis; and (II) superintense, high-frequency lasers that impel electrons to undergo quiver oscillations that interact with the intrinsic Coulomb forces and induce an extremely strong chemical bond. By including in II an excited electronic state, we bring out features amenable to experimental observation that has been lacking. Intense pulsed-laser fields have provided means to both induce spatial alignment of molecules and enhance strength of chemical bonds. The duration of the laser field typically ranges from hundreds of picoseconds to a few femtoseconds. Accordingly, the induced “laser-dressed” properties can be adiabatic, existing only during the pulse, or nonadiabatic, persisting into the subsequent field-free domain. We exemplify these aspects by treating the helium dimer, in its ground (X1Σg+) and first excited (A1Σu+) electronic states. The ground-state dimer when field-free is barely bound, so very responsive to electric fields. We examine two laser realms, designated (I) “intrusive” and (II) “impelling.” I employs intense nonresonant laser fields, not strong enough to dislodge electrons, yet interact with the dimer polarizability to induce binding and pendular states in which the dimer axis librates about the electric field direction. II employs superintense high-frequency fields that impel the electrons to undergo quiver oscillations, which interact with the intrinsic Coulomb forces to form an effective binding potential. The dimer bond then becomes much stronger. For I, we map laser-induced pendular alignment within the X state, which is absent for the field-free dimer. For II, we evaluate vibronic transitions from the X to A states, governed by the amplitude of the quiver oscillations.
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DOI：
10.1063/1.2207619
发表时间：
2006-05
期刊：
The Journal of chemical physics
影响因子：
--
作者：
Qi Wei;S. Kais;N. Moiseyev
通讯作者：
Qi Wei;S. Kais;N. Moiseyev
影响因子：
8.6
作者：
O. Smirnova;M. Spanner;M. Ivanov
通讯作者：
O. Smirnova;M. Spanner;M. Ivanov
DOI：
10.1063/1.3027451
发表时间：
2008-12
期刊：
The Journal of chemical physics
影响因子：
--
作者：
Qi Wei;S. Kais;D. Herschbach
通讯作者：
Qi Wei;S. Kais;D. Herschbach
影响因子：
4.4
作者：
Chandler, David W.;Houston, Paul L.;Parker, David H.
通讯作者：
Parker, David H.
影响因子：
2.9
作者：
Balanarayan, P.;Moiseyev, Nimrod
通讯作者：
Moiseyev, Nimrod