Pure beams of free radicals for studies of radical-surface chemistry

用于自由基表面化学研究的纯自由基束

• 批准号: EP/J010839/1
• 负责人: Stephen Price
• 金额: $ 119.79万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FJ010839%2F1
• 关键词: Pure; beams; free; radicals; studies

Free radicals, molecules with one or more unpaired electrons, are highly chemically reactive. This high reactivity means that free radicals exert a major influence on the chemistry of any environment in which they are formed, even though they are often not the most abundant species. For example, it is free radical chemistry that controls important atmospheric phenomena such as the ozone hole and the formation of photochemical smog.The interactions of free radicals with surfaces are thought to be vitally important in controlling the chemistry of formation of thin-films from electrical discharges, so called plasma-assisted deposition. Such thin-films have enormous technological importance in fields such as integrated circuits and solar cells. However, the details of the interactions of the radicals with the surfaces in these film formation processes are not well understood. The major hurdle to investigating this surface chemistry of free radicals is that, currently, there is no general technique available to dose a surface with only the free radical of interest, for example CH. Current radical sources generate the radicals from a precursor gas (e.g. CH from C2H2) and the precursor gas molecules always outnumber the radicals. Thus if a surface was dosed from a conventional radical source, the precursor molecules would be the dominant species on the surface, making it almost impossible to study the interactions of the radical with the surface using standard surface science techniques.In this application, we propose the development of a new source of free radicals which will generate "clean" beams of the radical species, uncontaminated by the precursor molecule. The source will work by generating negative ions (e.g. CH-), which can be mass selected to form a clean beam. The radicals are then generated from the negative ions by using a laser beam to knock off the electron. This photo-detachment of negative ions will yield a clean beam of the radical species of interest. Calculations given in the proposal show that a practical flux of free radicals can be generated by this methodology.The clean beams of free radicals can then be used to dose the surface with the radical species, and the surface can be studied using the standard techniques of surface science to reveal the details of the radicals sticking and surface chemistry. We propose to develop the source and then use it to study the radical-surface interactions involved in three technologically important film deposition processes. The chemistry revealed by our investigations will dramatically improve our understanding of what is going on in these industrially relevant surface reactions and allow us to optimize and refine these deposition processes in the light of the chemistry that is occurring.

自由基，一个或多个未配对电子的分子是高度化学反应性的。这种高反应性意味着自由基对形成的任何环境的化学反应产生重大影响，即使它们通常不是最丰富的物种。例如，自由基化学反应控制着重要的大气现象，例如臭氧孔和光化学烟雾的形成。自由基与表面的相互作用被认为在控制来自电气放电的薄膜化学的化学中至关重要。这种薄膜在诸如综合电路和太阳能电池等领域具有巨大的技术重要性。但是，在这些膜形成过程中激进分子与表面的相互作用的细节尚不清楚。研究这种自由基表面化学的主要障碍是，目前尚无通用技术可用于仅具有感兴趣的自由基的表面，例如CH。电流自由基来源从前体气体（例如C2H2的CH）产生自由基，而前体气体分子总是超过自由基。因此，如果表面是从常规的自由基来给出的，那么前体分子将是表面上的主要物种，几乎不可能使用标准表面科学技术研究激进的与表面的相互作用。在这项应用中，我们提出了一种新的自由基的发展，这些自由基的发展将产生“清洁”的“清洁”束，而不是由先前的solecorecules solecersorecorsorerorecorsororerorecorsororerororororerorecor。源将通过产生负离子（例如CH-）来起作用，可以选择质量以形成干净的光束。然后，通过使用激光束将电子击倒电子，从负离子中产生自由基。否定离子的这种光检测将产生一种令人兴奋的激进物种的清洁光束。提案中给出的计算表明，该方法可以生成自由基的实际通量。然后可以使用自由基的清洁光束用自由基物种对表面进行剂量，并可以使用表面科学的标准技术来研究表面，以揭示自由基粘附和表面化学的细节。我们建议开发源，然后使用它来研究三个技术上重要的膜沉积过程中涉及的自由基相互作用。通过我们的研究揭示的化学反应将大大提高我们对这些与这些工业相关的表面反应正在发生的情况的理解，并允许我们根据正在发生的化学反应来优化和完善这些沉积过程。

项目成果

Electron ionisation of cyanoacetylene: ionisation cross sections and dication formation

氰乙炔的电子电离：电离截面和双阳离子形成

• DOI: 10.1088/1361-6455/ac6781
• 发表时间: 2022
• 期刊: Atomic, Molecular and Optical Physics
• 作者: Ellis-Gibbings L

Bimolecular reactions of CH2CN2+ with Ar, N2 and CO: reactivity and dynamics.

CH2CN2 与 Ar、N2 和 CO 的双分子反应：反应性和动力学。

• DOI: 10.1039/d2cp01523d
• 发表时间: 2022
• 期刊: PCCP
• 作者: Armenta Butt S

Ionisation of PF3: absolute partial electron ionisation cross sections and the formation and reactivity of dication states.

PF3 的电离：绝对部分电子电离截面以及双阳离子态的形成和反应性。

• DOI: 10.1039/d1cp01328a
• 发表时间: 2021
• 期刊: PCCP
• 作者: Ellis-Gibbings LK

Bond-forming and electron-transfer reactivity between Ar2+ and O2.

• DOI: 10.1039/d0cp01194k
• 发表时间: 2020-04
• 期刊: Physical chemistry chemical physics : PCCP
• 作者: Sam Armenta Butt;S. Price

The surface reactivity of acrylonitrile with oxygen atoms on an analogue of interstellar dust grains

丙烯腈与氧原子在星际尘埃颗粒类似物上的表面反应性

• DOI: 10.1093/mnras/sty587
• 发表时间: 2018
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Kimber H