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，涉及到有机化合物的易氧化，并正在被揭示为一个复杂的和具有挑战性的大气化学课题。气溶胶-气候相互作用是气候强迫[IPCC]不确定性的一个关键来源，通过云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预测气候敏感性的能力（由给定强迫引起的全球平均温度变化）。由于自然大气中发生的化学机制的范围，化学家可以选择在室的可控环境中研究氧化和冷凝步骤，通常与所需的一组分析仪器连接，以使颗粒形成、冷凝和生长的过程能够被最佳地研究。该项目下的工作旨在提高对涉及低挥发性碳氢化合物（例如萜烯-臭氧加合物）与硫酸簇相互作用的颗粒形成步骤的理解。研究生将进行一系列的测量，沿着光化学建模，在室都在匹兹堡（CMU），和欧洲核子研究中心的欧洲云（宇宙离开户外液滴）大气设施。

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.