Studies on the physicochemical properties of adsorbed organic adlayers as mimics for atmospheric organic-coated aerosols using fourier transformed infrared spectroscopy

低层大气，即对流层，由大量微小的空气悬浮粒子（即气溶胶）组成。对流层中的气溶胶具有复杂的化学成分，它们在许多方面影响着我们的生活。雾霾天气能见度降低和呼吸道健康问题只是气溶胶对区域影响的两个例子。在全球范围内，气溶胶对气候变化有贡献，因为它们影响到达地球表面的阳光数量，改变云的性质，并为大气中的化学反应提供媒介。对气候的计算机模拟使我们能够量化气溶胶对气候变化的影响程度。然而，在这些模拟中，气溶胶的表征仍然不够充分，主要是因为气溶胶本质上很复杂，它们在空气中悬浮时的反应性和性质随时间而变化。因此，必须通过实验研究来解决与气溶胶有关的科学问题，以更好地了解气溶胶对气候系统的影响。本提案所要求的资金将用于解决一个重要的科学问题，即气溶胶颗粒的处理和老化，特别是那些被有机物质包裹的颗粒。气溶胶上的有机物来源于人类活动、自然来源（树木和动物的排放）和生物质燃烧造成的污染。由于反应主要发生在气溶胶表面，为了简化气溶胶复杂的化学性质，我们将使用由真实气溶胶颗粒中发现的最丰富的化合物组成的模型表面。气溶胶的加工和老化主要是与大气中的污染气体发生反应引起的。我们将使用实验技术，允许在尽可能接近大气条件的受控环境下监测表面上的反应，以便结果可以外推到“真实世界”系统。从这些研究中获得的结果将增加我们对气溶胶老化过程及其对全球气候的总体影响的理解。

The lower atmosphere, known as the troposphere, comprises a large concentration of minute airborne particles known as aerosols. Aerosols in the troposphere have complex chemical composition and they impact our lives in a number of ways.  Reduced visibility seen on hazy days and respiratory health problems are just two examples of aerosols impact on a regional scale.  On a global scale, aerosols contribute to climate change as they influence the amount of sunlight reaching the Earth's surface, alter properties of clouds, and provide media for chemical reactions in the atmosphere.  Computer simulations of the climate give us the capability of quantifying the magnitude of aerosols contribution to climate change. Yet aerosols representation in these simulations is still inadequate mainly because aerosols are complicated in nature and their reactivity and properties change with time while suspended in air.  Thus, it is imperative to address scientific questions related to aerosols through experimental studies to better our understanding of the aerosols impact on our climate system. The funding requested in this proposal will be used to tackle an important scientific problem, which is the processing and aging of aerosol particles, especially those coated with organic matter.  Organic matter on aerosols originates from pollution stemming from human activity, natural sources (emissions from trees and animals), and biomass burning. Since reactions occur mainly on aerosols surfaces, and in order to simplify the complex chemical nature of aerosols, we will work with model surfaces composed of the most abundant chemical compounds identified in real aerosol particles.  The processing and aging of aerosols are mainly caused by reactions with pollutant gases found in the atmosphere.  We will use experimental techniques that allow monitoring reactions on surfaces under controlled environments as close as possible to atmospheric conditions, so that results can be extrapolated to the "real world" system.  Results obtained from these studies will increase our understanding of the aging process of aerosols and their overall impact on the global climate.