Atom and molecule emission caused by ion impact into a frozen oxygen target: Role of rovibrational excitation

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• 作者：Christian Anders ; Roman Pedrys ; Herbert M. Urbassek
• 关键词：Sputtering ; Molecular dynamics simulation ; Molecule emission ; Oxygen
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：15 November, 2013
• 年：2013
• 卷：315
• 期：Complete
• 页码：308-312
• 全文大小：704 K

文摘

Translational energy distributions of particles sputtered by 750 eV Ne⁺ ion impact into a cryogenic O₂ target are studied using molecular-dynamics simulation. When comparing the energy distribution of emitted molecules to a Thompson distribution, good agreement can only be found for energies m>Em> with , where m>Um> is the surface binding and m>Dm> the dissociation energy of oxygen molecules. At smaller energies, a strong spike contribution enhances the spectrum. At higher energies ( eV), simulation shows a deficiency in sputtered molecules compared to the Thompson distribution; we show that this can be traced back to the decay of highly rovibrationally excited molecules after emission. Around 2% of the sputtered particles consist of radicals (atomic O). These originate from direct projectile-molecule collisions; they are emitted early in the collision cascade and feature a strong high-energy contribution.