About the Seminar:

Chemical behaviors vary between confined and bulk environments. Understanding facets such as diffusion and adsorption/desorption within confined environments provides crucial insight into behaviors that can be found in biological systems such as proteins and cell membranes. This kind of chemistry can also be observed in model systems such as reverse micelles or materials such as nanoporous silica. Silica nanoparticles are covered in pores that can be used to model confinement of solutions and their dynamics. With applications including chromatography, water purification, and materials design, research into a confined environment will prove useful. Fluorescence correlation spectroscopy (FCS) was utilized to observe single rhodamine 6G (R6G) molecule interparticle diffusion through nanoporous silica particles at equilibrium. Autocorrelation fitted with a two-component model displayed a fast diffusion component with the R6G diffusing through pores with little to no adsorption/desorption. While the slow diffusion component exhibited adsorption/desorption to the pore walls. Surface diffusion was ruled out as a mode of diffusion. Thus, the two-component FCS model suggest that in nanoporous silica, confinement and solution conditions primarily influence the rate of the fast minimally hindered pore diffusion, while the slow adsorption-desorption limited pore diffusion of R6G remained largely unaffected.