Gas phase studies of the kinetics of Criegee Intermediates

Criegee 中间体动力学的气相研究

• 批准号: NE/K004905/1
• 负责人: Dudley Shallcross
• 金额: $ 49.18万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK004905%2F1
• 关键词: Gas; phase; studies; kinetics; Criegee

The Earth's atmosphere is a complex mixture of gases, liquids and even solids. This mainly gaseous envelope around us performs many vital functions e.g. it protects us from harmful ultraviolet light (high energy light) from the Sun through the stratospheric ozone layer. Through the water cycle, clouds are formed in the atmosphere that redistributes water in the Earth systems. These clouds also cool the planet by acting like mirrors, reflecting some of the energy from the Sun back to outer space. This cooling mechanism is essential to the Earth system to permit an equitable surface temperature to exist that allows all the diverse life forms on it to exist. As well as this natural cooling mechanism, so called greenhouse gases in the atmosphere (e.g. carbon dioxide, CO2 and methane CH4) absorb infrared energy released by the Earth and trap some of it, very similar to the analogy of putting on a blanket and warm the Earth's surface up. Both these natural cooling and warming mechanisms are essential to a habitable surface and as long as they stay in balance, the surface temperature will remain reasonably constant. However, over the last 200 years humans have been increasing the level of greenhouse gases in the atmosphere by burning fossil fuels and evidence shows that this is leading to an overall warming of the surface of the Earth. The consequences of even a modest increase in average global surface temperature are significant for human, animal and plant life.It is known that chemicals released naturally by plants (unsaturated organic molecules such as alkenes) can react with oxidants in the atmosphere to produce extremely fast reacting intermediates, so called Criegee intermediates (CI). However, recent studies by us have shown that these Criegee intermediates react rapidly with a number of species present in the atmosphere such as sulphur dioxide (SO2). Ultimately, these reactions lead to the formation of sulphuric acid, which is very good at promoting aerosol formation (cloud precursors). Under polluted environments, aerosol formation may have detrimental effects on health but in the background atmosphere, promotion of cloud formation leads to a cooling of the Earth's surface. We have assessed the possible impact of these natural emissions of chemicals using computer models of the atmosphere and it appears that this process may be very important in producing cloud precursors and therefore be having an important impact on the Earth's climate (cooling it). However, we have only been able to investigate the reactions of two possible Criegee intermediates and there are potentially thousands of different ones. Whilst it would be impossible to study them all and indeed not a sensible endeavour, it is important to study different types of Criegee intermediates. If they all have a similar reactivity then the impact on the atmosphere is likely to be true and would then be important to include in climate models. In order to investigate how quickly these Criegee intermediates react with species such as SO2 we have devised an experiment in the laboratory that takes advantage of recent developments in optics. Using laser light to generate these Criegee intermediates we will be able to detect them using a highly sensitive technique called cavity ringdown spectroscopy (CRDS). In the experiment the Criegee intermediate is generated in a closed system where light is trapped between two highly reflective mirrors. As the light bounces backwards and forwards between the mirrors it may be absorbed by the Criegee intermediate and so less light is left. The greater the level of Criegee intermediate made the less light is reflected back and forth and so we have a way to measure this species. In this way we will be able to investigate how fast these Criegee intermediates react with a number of important gases in the Earth's atmosphere.

地球的大气是气体，液体甚至固体的复杂混合物。我们周围的主要气态包膜执行许多重要功能，例如它通过平流层臭氧层保护我们免受太阳的有害紫外线（高能光）。通过水循环，在重新分配地球系统中水的大气中形成云。这些云也通过像镜子一样的作用来冷却地球，从而反映出从太阳回到外太空的一些能量。这种冷却机制对于地球系统至关重要，即使公平的表面温度允许其上所有不同的生命形式存在。除了这种天然冷却机制外，在大气中所谓的温室气体（例如二氧化碳，二氧化碳和甲烷CH4）吸收了地球释放的红外能量并捕获其中的一些，与放在毯子上并温暖地球表面的类比非常相似。这些天然冷却和变暖机制对于可居住的表面至关重要，只要它们保持平衡，表面温度将保持相当恒定。但是，在过去的200年中，人类通过燃烧化石燃料来增加大气中的温室气体水平，证据表明，这导致了地球表面的整体变暖。即使是平均全球表面温度的适度升高，对人，动物和植物寿命也很重要。众所周知，植物（不饱和有机分子（例如烷烃））自然释放的化学物质可以与大气中的氧化剂反应，从而产生非常快速的中间体，即称为Criegee中间体（CI）。但是，我们最近的研究表明，这些Criegee中间体与大气中存在的许多物种（例如二氧化硫（SO2））迅速反应。最终，这些反应导致硫酸的形成，这非常擅长促进气溶胶形成（云前体）。在受污染的环境下，气溶胶形成可能会对健康产生不利影响，但在背景大气中，促进云形成​​会导致地球表面冷却。我们已经使用大气的计算机模型评估了这些化学物质自然排放的可能影响，并且看来该过程在产生云前体可能非常重要，因此对地球的气候产生了重要影响（冷却它）。但是，我们只能研究两个可能的Criegee中间体的反应，并且可能有数千个不同的中间体。尽管不可能全部研究它们，而且确实不是一项明智的努力，但研究不同类型的Criegee中间体很重要。如果它们都具有相似的反应性，那么对大气的影响可能是正确的，然后将其包括在气候模型中很重要。为了研究这些Criegee中间体与SO2等物种的反应速度，我们设计了一个实验室中的实验，利用了光学方面的最新发展。使用激光光生成这些Criegee中间体，我们将能够使用一种称为“腔度环光谱”（CRDS）的高敏感技术检测它们。在实验中，Criegee中间体是在封闭的系统中生成的，在封闭的系统中，光被捕获在两个高度反射镜之间。当镜子之间的光反向前进和向前弹跳时，它可能被Criegee中级吸收，因此剩下的光线更少。 Criegee中间体的水平越大，来回反映的光线越少，因此我们有一种测量该物种的方法。通过这种方式，我们将能够研究这些Criegee中间体与地球大气中许多重要气体的反应速度。

项目成果

Ground and Airborne U.K. Measurements of Nitryl Chloride: An Investigation of the Role of Cl Atom Oxidation at Weybourne Atmospheric Observatory

• DOI: 10.1002/2017jd026624
• 发表时间: 2017-10
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: T. Bannan;A. Bacak;Michael Le Breton;M. Flynn;B. Ouyang;M. McLeod;Roderic L. Jones;T. L. Malkin;L. Whalley;D. Heard;B. Bandy;M. Khan;D. Shallcross;C. Percival

The reaction of hydroxyl and methylperoxy radicals is not a major source of atmospheric methanol.

• DOI: 10.1038/s41467-018-06716-x
• 发表时间: 2018-10-19
• 期刊: Nature communications
• 影响因子: 16.6
• 作者: Caravan RL;Khan MAH;Zádor J;Sheps L;Antonov IO;Rotavera B;Ramasesha K;Au K;Chen MW;Rösch D;Osborn DL;Fittschen C;Schoemaecker C;Duncianu M;Grira A;Dusanter S;Tomas A;Percival CJ;Shallcross DE;Taatjes CA
• 通讯作者: Taatjes CA

Impact of Criegee Intermediate Reactions with Peroxy Radicals on Tropospheric Organic Aerosol

• DOI: 10.1021/acsearthspacechem.0c00147
• 发表时间: 2020-10-15
• 期刊: ACS EARTH AND SPACE CHEMISTRY
• 影响因子: 3.4
• 作者: Chhantyal-Pun, Rabi;Khan, M. Anwar H.;Orr-Ewing, Andrew J.
• 通讯作者: Orr-Ewing, Andrew J.

Importance of direct anthropogenic emissions of formic acid measured by a chemical ionisation mass spectrometer (CIMS) during the Winter ClearfLo Campaign in London, January 2012

• DOI: 10.1016/j.atmosenv.2013.10.029
• 发表时间: 2014-02-01
• 期刊: ATMOSPHERIC ENVIRONMENT
• 影响因子: 5
• 作者: Bannan, Thomas J.;Bacak, Asan;Percival, Carl J.
• 通讯作者: Percival, Carl J.

Temperature-Dependence of the Rates of Reaction of Trifluoroacetic Acid with Criegee Intermediates.

三氟乙酸与Criegee中间体反应速率的温度依赖性。

• DOI: 10.1002/anie.201703700
• 发表时间: 2017-07-24
• 期刊: Angewandte Chemie (International ed. in English)
• 作者: Chhantyal-Pun R;McGillen MR;Beames JM;Khan MAH;Percival CJ;Shallcross DE;Orr-Ewing AJ
• 通讯作者: Orr-Ewing AJ