Phase transitions and heterogeneous chemistry of tropospheric aerosols

总的来说，我们的研究将集中在大气化学上，总体目标是提高对大气中重要过程的理解。我们拟议的研究的第一部分将探索大气气溶胶颗粒从液体转化为固体以及反之亦然的条件。换句话说，我们将探索对大气具有重要意义的气溶胶颗粒的相变。在这些研究中，我们将重点关注与自由对流层相关的温度下的有机-无机混合颗粒，自由对流层是大约1公里至18公里高的大气区域。关于颗粒相(即固体或液体)的知识对于预测颗粒的反应性以及颗粒对气候的影响是必要的。我们的实验室研究可能对预测大气中卷云的形成也很重要。我们提议的研究的第二部分将探索气相物种与气溶胶颗粒之间的反应，称为非均相化学。我们要研究的具体反应包括N2O5与涂有有机薄膜的水气溶胶颗粒之间的反应，以及N3自由基与有机颗粒的反应。这些研究的信息可能会改进对大气中N2O5、N03和O3浓度的预测。此外，我们的研究可能对预测大气中有机颗粒的寿命和预测多环芳烃等有毒物种的命运也很重要。它们在大气中含量丰富。

In general our research will focus on atmospheric chemistry with an overall goal of improving the understanding of important processes in the atmosphere.The first part of our proposed research will explore the conditions at which atmospheric aerosol particles transform from liquid to solid and vice versa.  In other words, we will explore phase transitions of aerosol particles that are of atmospheric importance.  In these studies we will focus on mixed organic-inorganic particles at temperatures relevant for the free troposphere, which is the region of the atmosphere between approximately 1 km and 18 km in height. Knowledge of the particle phase (i.e. solid or liquid) is necessary to predict the reactivity of particles and also the impact of particles on climate. Our laboratory studies may also be important for predicting the formation of cirrus clouds in the atmosphere.  The second part of our proposed research will explore reactions between gas-phase species and aerosol particles, termed heterogeneous chemistry.  Specific reactions to be studied include the reaction between N2O5 and aqueous aerosol particles coated with organic films and NO3 radicals with organic particles.  Information from these studies may lead to improved predictions of N2O5, NO3, and O3 concentrations in the atmosphere.   Our research may also be important for predicting the lifetime of organic particles in the atmosphere and for predicting the fate of toxic species such as polycyclic aromatic hydrocarbons, which are abundant in the atmosphere.