Analytical Chemistry Seminar: Ryan Davis
Jointly sponsored by the Department of Chemistry and Biochemistry, CIRES, and the Environmental Program
Novel Phase Transitions of Optically Levitated Microdroplets: Contacts and Glasses Relevant to the Atmosphere
Ryan Davis, University of Colorado
The phase state and water content of atmospheric particles influence the particle's size, optical properties and chemical reactivity with important but poorly constrained effects on air quality and climate. One challenging problem is predicting the ambient conditions required to initiate a phase transformation of a particle from liquid to solid, particularly when consideration is given to multi-particle interactions as well as chemical composition of the liquid droplet. One such example is the phenomenon of contact nucleation. Presented here are the first direct observations of contact nucleation of crystalline ammonium sulfate using a recently developed long-working distance optical trap. Insight is given to the mechanism behind contact nucleation. The effect of amorphous or glassy phase states will also be discussed.