Molecular level observation of nucleation in binary vapors

Abstract:

Nucleation is a ubiquitous phenomenon that leads to new particle formation in both Earth’s and Mars’ atmospheres. Experimental attempts to elucidate nucleation mechanisms on the molecular level have mostly been focused on species that interact to form relatively strongly bound clusters, with a bias in detected cluster concentrations due to fragmentation. Here, we report experiments designed to minimize cluster fragmentation, extending the scope of molecular inspection on nucleation to species that enhance nucleation even though they form only weakly-bound, metastable clusters with the nucleating vapor molecules. The CO₂-containing model systems we study are relevant to Mars’ atmosphere, but more importantly, the experimental and analytical methods we present here open a new avenue to the quantitative analysis of nucleation.