(296c) Analysis of Fluid Flow and Mass Transport During AFM Measurements of Solution Crystal Growth

Derby, J. J., University of Minnesota
Yeckel, A., University of Minnesota
Wang, W., University of Minnesota

Atomic force microscopy (AFM) fluid cell has become a prominent experimental tool for in situ measurements of crystal faces growing from solution phase, and even providing near real time observations with the newly developed fast-scanning scanner. This technique has been used to investigate micro-scale features of solution crystal growth of various organic and inorganic crystals, including imaging of terraces, ledges, and kinks, and the direct measurement of kink and step velocities. These measurements permit estimates of thermodynamic and kinetic properties of solution crystal growth. However, the crystallization conditions present in the AFM fluid cell would need revise while AFM measurements are being conducted, especially in the fast-scanning AFM systems, as a result of potential mass transport limitations being experienced by the crystal and the effect of flows that are driven by scanner motion.

Using a parallel, finite element model validated in prior work, we present detailed, three-dimensional computations of fluid flow and mass transfer through an AFM fluid cell to access the parametric sensitivity of growth conditions to factors such as the strength of flow, the direction and frequency of scanner motion, the size of the crystal, the kinetics of the growing surface, and the geometry of the AFM cantilever. Accounting for such effects will be very important to interpret AFM measurements of growth dynamics.