自由氙团簇中体激子和表面激子的发光证据
Luminescence evidence for bulk and surface excitons in free xenon clusters
摘要：
本文研究了氙-氩混合气体在超音速射流中凝结产生的自由氙团簇的阴极荧光光谱。通过改变初始实验参数，包括氙的浓度，我们可以得到的集群与氙核心（300-3500原子）所覆盖的氩气外壳，以及无壳氙集群（约1500个原子）。用电子照相法测量了团簇的大小和温度（两种情况下约为40 K）。无壳氙团簇的发光带证明存在的体和表面激子检测。小团簇中体激子的发射是由于它们在氙-真空界面的多次弹性反射过程。氩壳层的存在导致激子带的消失。此外，还发现了一些新的谱带，这些谱带与体氙冷冻样品没有类似物。
英文摘要：
Cathodoluminescence spectra of free xenon clusters produced by condensation of xenon-argon gas mixtures in supersonic jets expanding into vacuum were studied. By varying initial experimental parameters, including xenon concentration, we could obtain clusters with a xenon core (300-3500 atoms) covered by an argon outer shell as well as shell-free xenon clusters (about 1500 atoms). The cluster size and temperature (about 40 K for both cases) were measured electronographically. Luminescence bands evidencing the existence of bulk and surface excitons were detected for shell-free xenon clusters. The emission from bulk excitons in small clusters is supposed to be due to processes of their multiple elastic reflections from the xenon-vacuum interface. A presence of an argon shell causes extinction of the excitonic bands. In addition, some new bands were found which have no analogs for bulk xenon cryosamples.
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