INFAMOS - a new method for speciated peroxy radical detection

INFAMOS - 一种检测形态过氧自由基的新方法

基本信息

批准号：
NE/M011208/1
负责人：
Dwayne Heard
金额：
$ 52.84万
依托单位：
University of Leeds
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FM011208%2F1
关键词：
INFAMOS new method speciated peroxy

项目摘要

The international societal response to deteriorating air quality and the changing climate is guided by the predictions of numerical models. These models contain estimates of future emissions of trace gases and aerosols from natural processes and human activities, their dispersal throughout the atmosphere, and their chemical transformations into a wide range of secondary products.Photo-oxidation in the troposphere is highly complex, being initiated by short lived radical species, in the daytime dominated by the hydroxyl radical, with contributions from chlorine atoms, and at night by either the nitrate radical or ozone. Fast chemical oxidation cycles remove trace species which are harmful to humans and to the wider environment. Many secondary products produced by atmospheric photo-oxidation are also directly harmful, for example ozone, nitrogen dioxide, acids and multifunctional organic molecules, many of which are of low volatility and are able to partition effectively to the condensed phase, creating secondary organic aerosol, with associated impacts on climate and human health. One of the best ways to test the accuracy of a chemical mechanism used in an air quality or climate model is to compare its calculated output for radical species for a given location and time with actual measurements made in the atmosphere. Radicals are ideal for this purpose as their lifetimes are short, and hence are controlled by chemistry rather than by transport.Two of the simplest radicals in the atmosphere are the hydroperoxy radical, HO2, and the smallest and dominant organic peroxy radical, CH3O2, which are formed directly by the reactions of OH with carbon monoxide and methane. Their reaction with nitric oxide constitutes the only tropospheric in situ source of O3, a respiratory irritant and a greenhouse gas. Despite their importance, neither HO2 nor CH3O2 are measured directly in the atmosphere, with HO2 only being determined indirectly following conversion first to OH after sampling.This proposal brings together leading expertise from a field measurement group at Leeds and a cavity enhanced optical spectroscopy group at Oxford to tackle this gap. The overarching aim is to develop a novel and direct laser spectroscopic technique called INFAMOS which has the potential to measure the concentrations of HO2 and CH3O2 in the field. An intercomparison of INFAMOS with complementary, but indirect, chemical conversion methods will be carried out in the Leeds HIRAC atmospheric chamber (volume 2250 litres), whose capabilities will also be improved via this proposal. The new technique will also be used to make direct, sensitive measurements of HO2 and CH3O2 in HIRAC to study the kinetics and product yields for several key atmospheric reactions which are poorly quantified, in conjunction with rate theory calculations and box modelling using the Master Chemical Mechanism.The newly developed technique to measure HO2 or CH3O2 will also have potential benefits in other areas, for example to understand fundamentals of combustion chemistry in the energy sector.

国际社会对空气质量恶化和气候变化的反应是由数值模型的预测指导的。这些模型包含对自然过程和人类活动中微量气体和气溶胶未来排放、它们在整个大气中的扩散以及它们化学转化为各种次级产品的估计。对流层中的光氧化非常复杂，由短寿命的自由基种类，白天以羟基自由基为主，并有氯原子的贡献，而在夜间则以硝酸根或臭氧为主。快速化学氧化循环可去除对人类和更广泛环境有害的微量物质。大气光氧化产生的许多二次产物也是直接有害的，例如臭氧、二氧化氮、酸和多功能有机分子，其中许多具有低挥发性，能够有效地分离成凝相，产生二次有机气溶胶，对气候和人类健康产生相关影响。测试空气质量或气候模型中使用的化学机制准确性的最佳方法之一是将给定地点和时间的自由基物种的计算输出与大气中的实际测量结果进行比较。自由基是实现此目的的理想选择，因为它们的寿命很短，因此由化学而不是传输控制。大气中两个最简单的自由基是氢过氧自由基 HO2 和最小且占主导地位的有机过氧自由基 CH3O2，由 OH 与一氧化碳和甲烷反应直接形成。它们与一氧化氮的反应构成了 O3 的唯一对流层原位来源，O3 是一种呼吸刺激物和温室气体。尽管它们很重要，但 HO2 和 CH3O2 都不能在大气中直接测量，只有在采样后首先转化为 OH 后才能间接测定 HO2。该提案汇集了利兹现场测量小组和利兹大学腔增强光谱小组的领先专业知识。牛津大学致力于解决这一差距。总体目标是开发一种称为 INFAMOS 的新型直接激光光谱技术，该技术有潜力测量现场 HO2 和 CH3O2 的浓度。 INFAMOS 与补充但间接的化学转化方法的相互比较将在利兹 HIRAC 大气室（体积 2250 升）中进行，其能力也将通过该提案得到改进。该新技术还将用于在 HIRAC 中对 HO2 和 CH3O2 进行直接、灵敏的测量，以研究量化较差的几个关键大气反应的动力学和产物产率，并结合速率理论计算和使用主化学机理的盒建模新开发的测量 HO2 或 CH3O2 的技术还将在其他领域带来潜在的好处，例如了解能源领域燃烧化学的基础知识。