Transition metal ion (TMI) organic complexes photochemistry in tropospheric aerosols and clouds

自1992年第一次地球峰会以来，不同的国家已经认识到气候受到人类活动的强烈影响，并计划根据国际公约解决这一问题。在这方面，由联合国领导的缔约方会议（cop）将各国聚集在一起作出承诺。然而，为了采取有意义的行动，重要的是全世界的科学家为政策提供有用的数据，作为决策的基础。正是在这种更广泛的背景下，REACTE项目被提出，涉及国际公认的法国和德国在各自高度互补的科学领域的研究人员。大气是一个复杂和高度反应的系统，许多生物物理化学过程在其中发生。因此，对这一系统及其根据不同输入而发生的变化有充分的了解是至关重要的。为了更好地理解大气多相体系的发展，氧化还原反应是应认真考虑的主要转化途径之一。过渡金属离子（TMIs）的化学性质，它是含水气溶胶粒子和对流层云滴中高活性物质的主要来源。事实上，目前关于这些金属的确切作用和反应性的数据很少，目前在模型中几乎只考虑它们的自由形态，而已知它们在自然环境中以复合物的形式存在。REACTE打算回答以下问题：i) tmi的络合如何直接通过金属和/或与H2O2作为“Fenton”型反应影响其光反应性和氧化还原反应；ii)与这些反应相关的活性物质是什么，H2O2， HxOy自由基和它们的生成产率？它们会对大气的氧化能力产生什么影响，从而更普遍地影响大气的化学成分？得到的结果将在一个涉及化学水相自由基机制（CAPRAM）的多相大气化学模型中实施，以预测它们对大气液滴或气溶胶中有机质转化、HOx平衡和tmi价态的影响。REACTE项目结合了互补的科学能力，将使人们能够更好地了解大气颗粒中存在的TMI复合物的化学性质，从而了解它们在大气多相化学中的作用。

Since 1992 and the first Earth summit, different countries have recognized that climate is strongly impacted by human activity and they planned to tackle it under an international convention. In this context, ledby the United Nations, COPs (Conference of parties) bring together countries to make commitments. However, in order to take meaningful action, it is important that scientists worldwide provide useful data to policy as a basis for decisions. It is in this wider context that the REACTE project, involving internationally recognized French and German researchers in their respective highly complementary scientific fields, is proposed.The atmosphere is a complex and highly reactive system where many bio-physicochemical processes take place. It is therefore crucial to have a sound understanding of this system and its changes according to the different inputs it is subjected to. Redox reactions are one of the major transformation pathways that should be carefully considered in order to better understand the development of the atmospheric multiphase system. The (photo)chemistry of transition metal ions (TMIs) which represents a major source of highly reactive species in water-containing aerosol particles and in tropospheric cloud droplets. Indeed, very little data currently exists on the exact role and reactivity of these metals, which are currently considered almost exclusively in their free form in models, whereas they are known to be present as complexes in natural environments. REACTE intends to answer the following questions: i) How will the complexation of TMIs influence their photo-reactivity and redox reactions directly through the metal and/or with H2O2 as "Fenton" type reactions; ii) What will be the reactive species associated with these reactions, H2O2, HxOy radicals and their formation yields? What will be their impact on the oxidative capacity of the atmosphere and thus on, more generally, its chemical composition? The obtained results will be then implemented in a multiphase atmospheric chemistry model involving the chemical aqueous-phase radical mechanism (CAPRAM) to predict their influence on the organic matter transformation, the HOx balance and the valence states of TMIs in atmospheric droplets or aerosols. The REACTE project, in combining complementary scientific competences, will allow to better understand the chemistry of the TMI complexes present in atmospheric particles and thus to understand their role in atmospheric multiphase chemistry.