Molecular Clusters [Dance Your PhD 2020/2021 OVERALL WINNER]

Authors: Jakub Kubečka, Ivo Neefjes, Vitus Besel et al. About: Jakub Kubečka, Ivo Neefjes, and Vitus Besel (Twitter: @Supervitux) are PhD students of Atmospheric Science at the Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Finland. All of their research revolves or has revolved around the computational study of atmospheric molecular clusters. Jakub particularly deals with searching for the low energy structures of molecular clusters, whereas Ivo studies their fragmentation in APi-TOF mass spectrometers. Vitus investigated the formation of ammonia—sulfuric acid clusters in his Master’s thesis, but for his PhD started to work on vapor pressures of organic molecules in the atmosphere. Dance Your PhD is a competition organized by Science Magazine: Covid: The filmmaking process was completely conducted in agreement with local COVID-19 rules. All filming was done with masks on or outdoors. The office scene as well as the dancers were filmed with only two people present, the dancer one person to operate the camera. Science: A majority of cloud condensation nuclei is made up of secondary aerosols. These form directly in the atmosphere from gaseous precursors, such as sulfuric acid and ammonia, creating molecular clusters and their subsequent growth. Due to the energy barrier present in these nucleation processes, not all molecules can simply collide, stick together, and grow further into large particles. Even water requires some condensation nuclei to form a cloud. Therefore, we have to examine which molecules after collision create enough stable clusters that do not immediately evaporate back. To study various cluster stabilities, one has to explore their configuration space (bearing all possible structures) and find the configuration present in the atmosphere. Further, quantum chemistry calculation can provide cluster free energies. If clusters have low free-formation energy, they are likely to form and survive in atmospheric conditions. However, a second aspect is the gas molecule concentrations (the material for the cluster formation). And thus, utilizing the Atmospheric Cluster Dynamic Code (ACDC), our group was able to show that, for instance, sulfuric acid with some base molecules, such as ammonia or dimethylamine, with various highly oxygenated organic molecules are responsible for most of the clouds, mountain/forest hazes or mists that appear from ‘nowhere’. We thank Faustine Cros and Matias Jääskeläinen for their huge help during the video/music creation. Additionally, our thanks go also to Hanna Vehkamäki, Stephany Mazon, Angelica Bianco, Tommaso Zanca, Juha Kangasluoma, Stephen Ingram, and Markus Juvonen.