How volatile components catalyze vapor nucleation

Gas phase nucleation is a ubiquitous phenomenon in planetary atmospheres and technical processes, yet our understanding of it is far from complete. In particular, the enhancement of nucleation by the addition of a more volatile, weakly interacting gaseous species to a nucleating vapor has escaped molecular-level experimental investigation. Here, we use a specially designed experiment to directly measure the chemical composition and the concentration of nucleating clusters in various binary CO2-containing vapors. Our analysis suggests that CO2 essentially catalyzes nucleation of the low vapor pressure component through the formation of transient, heteromolecular clusters and thus provides alternative pathways for nucleation to proceed more efficiently. This work opens up new avenues for the quantitative assessment of nucleation mechanisms involving transient species in multicomponent vapors.

Automated summary

This research used a specially designed experiment to directly measure the chemical composition and concentration of nucleating clusters in various binary CO2-containing vapors, finding that CO2 can catalyze nucleation of the low vapor pressure component by forming transient heteromolecular clusters, providing alternative pathways for more efficient nucleation. This work opens up new avenues for quantitatively assessing nucleation mechanisms involving transient species in multicomponent vapors.