Constraining the Role of Gas-Phase Organic Oxidation in New-Particle Formation

大气新粒子的形成，团簇生长导致二次气溶胶（SOA）的形成，涉及有机化合物的易氧化，是大气化学中一个复杂而具有挑战性的课题。气溶胶-气候相互作用是气候强迫不确定性的一个关键来源[IPCC]，它通过云的形成及其性质的直接和间接变化影响行星辐射平衡和气候。气溶胶辐射强迫项的不确定性限制了我们根据目前观测到的气候变化预估气候敏感性（由给定强迫引起的全球平均温度变化）的能力。由于在自然气氛中发生的化学机制的范围，化学家可能会选择在一个可控的环境中研究氧化和冷凝步骤，通常与一组所需的分析仪器相连接，以使颗粒形成、冷凝和生长的过程得到最佳研究。该项目的工作旨在提高对低挥发性碳氢化合物（例如萜烯-臭氧加合物）与硫酸团簇相互作用的颗粒形成步骤的理解。研究生将在匹兹堡大学（CMU）和欧洲核子研究中心（CERN）的欧洲云（Cosmics Leaving OUtdoor液滴）大气设施的室内进行一系列测量，以及光化学建模。

Atmospheric new-particle formation, cluster growth leading to secondary aerosol (SOA) formation, involves facile oxidation of organic compounds and is being revealed as a complex and challenging topic in atmospheric chemistry. Aerosol-climate interactions are a key source of uncertainty in climate forcing [IPCC], affecting both planetary radiation balances, and climate through direct and indirect changes in cloud formation and their properties. Uncertainty in aerosol radiative forcing terms limits our ability to project climate sensitivity (the global average temperature change caused by a given forcing) from currently observed climate change.Because of the range of chemical mechanisms occurring in natural atmospheres, chemists may choose to study the oxidation and condensation steps in the controllable environment of a chamber, typically interfaced to a desired set of analytical instruments to enable the progress of particle formation, condensation and growth to be optimally studied. Work under this project is directed towards improving understanding of particle formation steps involving interactions of low volatility hydrocarbons (e.g. terpene - ozone adducts) with sulfuric acid clusters. Graduate students will carry out a series of measurements, along with photochemical modelling, in chambers both at Pittsburgh (CMU), and the European CLOUD (Cosmics Leaving OUtdoor Droplets) atmospheric facility at CERN.