Institut für Ionenphysik und Angewandte Physik, Leopold Franzens-Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
Phys Chem Chem Phys. 2010;12(20):5219-24. doi: 10.1039/b924526j.
Electron attachment to CO₂ clusters performed at high energy resolution (0.1 eV) is studied for the first time in the extended electron energy range from threshold (0 eV) to about 10 eV. Dissociative electron attachment (DEA) to single molecules yields O(-) as the only fragment ion arising from the well known (2)Π(u) shape resonance (ion yield centered at 4.4 eV) and a core excited resonance (at 8.2 eV). On proceeding to CO₂ clusters, non-dissociated complexes of the form (CO₂)(n)(-) including the monomer CO₂(-) are generated as well as solvated fragment ions of the form (CO₂)(n)O(-). The non-decomposed complexes appear already within a resonant feature near threshold (0 eV) and also within a broad contribution between 1 and 4 eV which is composed of two resonances observed for example for (CO₂)(4)(-) at 2.2 eV and 3.1 eV (peak maxima). While the complexes observed around 3.1 eV are generated via the (2)Π(u) resonance as precursor with subsequent intracluster relaxation, the contribution around 2.2 eV can be associated with a resonant scattering feature, recently discovered in single CO₂ in the selective excitation of the higher energy member of the well known Fermi dyad [M. Allan, Phys. Rev. Lett., 2001, 87, 0332012]. Formation of (CO₂)(n)(-) in the threshold region involves vibrational Feshbach resonances (VFRs) as previously discovered via an ultrahigh resolution (1 meV) laser photoelectron attachment method [E. Leber, S. Barsotti, I. I. Fabrikant, J. M. Weber, M.-W. Ruf and H. Hotop, Eur. Phys. J. D, 2000, 12, 125]. The complexes (CO₂)(n)O(-) clearly arise from DEA at an individual molecule within the cluster involving both the (2)Π(u) and the core excited resonance.
首次在从阈值（0 eV）到约 10 eV 的扩展电子能量范围内，以高能量分辨率（0.1 eV）研究了 CO₂ 团簇的电子附加。对于单个分子的离解电子附加（DEA），仅从众所周知的（2）Π（u）形状共振（离子产率中心在 4.4 eV）和核心激发共振（在 8.2 eV）产生 O(-) 作为唯一的碎片离子。在进行 CO₂ 团簇时，除了生成单体 CO₂(-)之外，还生成了形式为（CO₂）（n）（-）的未离解复合物以及形式为（CO₂）（n）O(-)的溶剂化碎片离子。未分解的复合物已经在阈值附近的共振特征（0 eV）中出现，并且在 1 到 4 eV 之间的宽贡献中也出现，该贡献由两个例如对于（CO₂）（4）（-）在 2.2 eV 和 3.1 eV（峰最大值）观察到的共振组成。虽然在 3.1 eV 左右观察到的复合物是通过作为前体的（2）Π（u）共振与随后的团簇内松弛生成的，但在 2.2 eV 左右的贡献可以与最近在单个 CO₂ 中发现的共振散射特征相关联，在该特征中选择性激发了著名的费米偶联的较高能量成员[M. Allan，Phys。Rev。Lett.，2001，87，0332012]。如通过超超高分辨率（1 meV）激光光电离方法先前发现的那样，在阈值区域中形成（CO₂）（n）（-）涉及振动 Feshbach 共振（VFR）[E. Leber，S. Barsotti，I. I. Fabrikant，J. M. Weber，M.-W. Ruf 和 H. Hotop，Eur。Phys。J. D，2000，12，125]。复合物（CO₂）（n）O(-)显然是从团簇内单个分子的 DEA 产生的，涉及（2）Π（u）和核心激发共振。
