Penn Research Group
Environmental Solid State Chemistry • Nanocystalline Materials • Geochemical Cycling
Major Research Areas
Professor Penn's research group encompasses several areas, many of which involve collaborations with other research groups both at the U of MN - twin cities and beyond:
Elucidating the fundamental aggregation and growth mechanisms - especially nonclassical crystal growth mechanisms - of inorganic nanoparticles.
Characterizing the reactivity of natural and synthetic nanoparticles in environmentally relevant conditions.
Characterizing the magnetic behavior of iron oxide nanoparticles (e.g., natural and synthetic ferrihydrite, goethite, and magnetite).
Studying microplastics in environmental systems.
Designing materials for remediating water contaminated with metals, microplastics, organics, and more.
Designing and implementing effective curriculum to strengthen and improve middle school and high school students’ understanding of science and engineering.
Students in the Penn group use many state-of-the-art materials characterization methods, including in situ and ex situ transmission electron microscopy (TEM), in combination with a broad suite of correlative methods, to characterize solid-state changes resulting from reactions with both natural and anthropogenic chemicals. This enables us to quantitatively assess reactivity, reactive surface area, and how reactivity and reactive surface area evolve as reactions proceed and solution conditions change. In addition, materials collected from the field are used in parallel experiments so as to enable meaningful comparisons between the field and the lab.
Figure caption: Cryogenic transmission electron microscopy of oriented iron oxide nanocrystals in water. The uniform grey background is vitrified water, and the darker round objects are crystals of iron oxide. Images like these enable us to study crystal growth, nanoparticle aggregation, and more. Image is from Yuwono, V.M.; Burrows, N.D.; Soltis, J.A.; Penn, R.L., (2010). Oriented Aggregation: Formation and Transformation of Mesocrystal Intermediates Revealed, Journal of the American Chemical Society, 132, pp. 2163-2165. DOI 10.1021/ja909769a
Contact Information
Distinguished University Teaching Professor
Institute on the Environment Resident Fellow
Mental Health Advocate
rleepenn@umn.edu
(612) 626-4680
225 Smith Hall
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