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长期暴露于大气的多晶镍样品,经700℃2小时真空退火及常温和500℃暴露氧20—60L后,发现其表面将产生两种电子诱导脱附(ESD)氧正离子。所对应的电子能量阈值分别为29eV和23eV。我们认为,两种氧正离子的产生机制为俄歇诱导脱附。29eV阈能者对应于镍表面化学吸附氧的2s能级电子向真空中电离;而23eV阈能者则对应于表面层中未与镍化合的自由氧的2s电子向体内费密能级跃迁。Electron Stimulated Desorption (BSD) of O+ from polycrystal Ni surface was studied. The ESD O+ was measured after the Ni sample was annealed at 700℃ for two hour and then exposed to 20-60 L O2 at room temperature and 500℃ respectively. Two kinds of ESD O+ had been found with different electron energy thresholds (29 eV and 23 eV). It was concluded that the two O+s were due to Auger induced desorption and the two thresholds corresponded to O(2s) electron ionization energy and excitation energy respectively. The process of excitation, ionization and de-excitation was also discussed.
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