Simulating the Earth's Atmosphere in a Laboratory to Better Understand Cloud Nucleation and Fundamental Properties of Heterogenous Adsorption

Small atmospheric particles (aerosols, particulate matter) play a key role in Earth’s climate system. They can affect climate by scattering solar radiation directly back to space, leading to a cooling effect, or they can absorb solar and terrestrial radiation, leading to a warming effect.^[1] Furthermore, some aerosols can uptake enough water to nucleate cloud formation, which also plays a strong role in climate. This dual role of aerosols makes them one of the least understood components in large-scale climate models, creating large uncertainty in predicting future climate.^[1] Thus, the major goal of my research is to determine predictive models based on laboratory measurements to generalize complex processes, such as cloud nucleation, in the case of this project. In my laboratory, we have a manifold system built by several generations of undergraduate students capable of simulating Earth’s atmosphere. We can mix atmospheric gases, such as oxygen, nitrogen, water vapor, etc., in appropriate ratios to mimic atmospheric composition. We then pass those gases over a solid surface of interest; this mimics atmospheric gases passing over the surface of aerosols. Using the Diffuse Reflectance Infrared Fourier Transform Spectroscopy technique, we can characterize chemical and physical changes in real-time and at the molecular scale of the solid surface as these atmospheric gases interact and react with the solid. Using quantitative information from our spectra, we can also quantify the water uptake properties of the solid surface using the classic Brunauer-Emmet-Teller (BET) adsorption isotherm. In my talk, I will introduce our technique and highlight noteworthy results from undergraduate students and the future direction of our research.