Ponomaryov Alexey, Gumenchuk Galina, Savchenko Elena, Bondybey Vladimir E
Lehrstuhl für Physikalische Chemie II, Technische Universität München, Garching, Germany.
Phys Chem Chem Phys. 2007 Mar 21;9(11):1329-40. doi: 10.1039/b616441b. Epub 2007 Feb 5.
An irradiation of solid argon sample by electrons ionizes the Ar atoms, and part of the beam energy is stored in the solid mainly in the form of self-trapped Ar(2)(+) holes. The pre-irradiated samples are investigated by methods of the so called "activation spectroscopy". During their controlled warm-up three thermally stimulated effects are observed and, in our experiments, simultaneously monitored: a VUV emission resulting from neutralization of the Ar(2)(+) holes by electrons, an anomalous desorption of surface atoms, and an exoelectron emission. A comparison of experiments with linear and step-wise sample heating shows clearly that all three processes are intimately connected. The heating detraps electrons, which neutralize the Ar(2)(+) holes resulting in a bound-free emission of argon dimers, centered around 9.7 eV. The excess energy set free during this process may dislodge surface atoms leading to an anomalous, low temperature, pressure rise. Some of the electrons can also be directly extracted from the sample and detected as an exoelectron current. The experiments provide information about the depth of electron traps, and indicate that there is a nearly continuous distribution of trapping energies.
用电子束辐照固态氩样品会使氩原子电离，部分束流能量主要以自陷Ar(2)(+)空穴的形式存储在固体中。通过所谓的“激活光谱法”对预辐照样品进行研究。在对其进行可控加热升温过程中，观察到并在我们的实验中同时监测到三种热激发效应：电子使Ar(2)(+)空穴中和产生的真空紫外发射、表面原子的异常解吸以及外逸电子发射。对线性加热和逐步加热样品的实验比较清楚地表明，这三个过程紧密相关。加热使电子脱陷，电子中和Ar(2)(+)空穴，导致氩二聚体产生自由束缚发射，中心能量约为9.7电子伏特。此过程中释放的多余能量可能会使表面原子脱离，导致异常的低温压力升高。部分电子也能直接从样品中提取并作为外逸电子电流被检测到。这些实验提供了有关电子陷阱深度的信息，并表明存在几乎连续分布的俘获能量。
