Photoelectron imaging spectroscopy of the small sodium cluster anions Na3(-), Na5(-), and Na7(-).
Photoelectron imaging spectroscopy of the small sodium cluster anions Na3(-), Na5(-), and Na7(-).
复制标题
小钠簇阴离子Na3(-)、Na5(-)和Na7(-)的光电子成像光谱
DOI：
10.1021/jp5010902
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
B. v. Issendorff
中科院分区：
文献类型：
--
作者：
C. Bartels;C. Hock;R. Kuhnen;B. v. Issendorff
我们提出了一个光电子成像研究的小钠簇阴离子Na 3-，Na 5-，Na 7-在可见光和近紫外范围内的光子能量（hv= 1.64-4.28 eV）。由此产生的角分布是非常多样化的，并表现出强烈的依赖于光子能量;只有当hv> 3.5 eV时，它们才演变成在激光偏振方向上达到峰值的更均匀的分布。我们发现，不同的能量依赖性的分布有关的不同的角动量字符的束缚态。最低的单粒子状态的类凝胶特性导致在所有光子能量下平行于激光偏振的光电子发射，而较高状态的类p特性导致在阈值处基本上各向同性分布和随光子能量的强烈变化。接近分离阈值时，渐近角分布归因于维格纳定律的近似有效性，该定律指出光谱由具有最小角动量的分波主导。对于平面集群Na 5-，我们观察到的电子从两个平面内的p-样态分离的特征不同的行为，我们展示了这是如何与分子的对称性。我们的研究结果表明，一个简单的果冻状的分子轨道的描述是适当的三维集群Na 7-，尽管通常三重简并1 p水平的能量分裂。
We present a photoelectron imaging study of the small sodium cluster anions Na3–, Na5–, and Na7–at photon energies in the visible and near UV range (hv= 1.64–4.28 eV). The resulting angular distributions are remarkably diverse and exhibit a strong dependence on photon energy; only forhv> 3.5 eV do they evolve into more uniform distributions peaked in the direction of the laser polarization. We show that different energy dependencies of the distributions are related to different angular-momentum characters of the bound states. The jellium s-like character of the lowest single-particle states results in photoelectron emission parallel to the laser polarization at all photon energies, whereas the p-like character of the higher states leads to essentially isotropic distributions at threshold and a strong variation with photon energy. Close to the detachment threshold, the asymptotic angular distributions are attributed to the approximate validity of Wigner’s law, which states that the spectrum is dominated by the partial wave with the smallest angular momentum. For the planar cluster Na5–, we observe characteristically different behavior for electrons detached from the two in-plane p-like states, and we show how this correlates with the molecular symmetry. Our results indicate that a simple jellium-like description of the molecular orbitals is appropriate for the three-dimensional cluster Na7–, despite the energetic splitting of the normally triply degenerate 1p level.