Environmental Solid State Chemistry - Nanocystalline Materials - Geochemical Cycling

Research People Publications Vita Teaching Characterization Facility

Cryo TEM images
Cryogenic transmission electron micrographs of iron oxide nanoparticles in vitrified water. The image on the left is a cryo-TEM of the freshly prepared nanoparticles after dialysis. The images on the right-hand side show mesocrystals composed of ca. 5 nm goethite nanoparticles in crystallographic alignment with respect to one another. This work is presented in Yuwono et al., 2010 and presented, for the first time, images of the intermediate proposed in the oriented aggregation crystal growth mechanism.


Assembly of dicobalt and cobalt-aluminum oxide clusters on metal-organic framework and nanocast silica supports, Sai Puneet Desai, Camille Malonza, Thomas Webber, JX Duan, Anthony B Thompson, Stephen J. Tereniak, Matthew R. DeStefano, Cassandra T. Buru, Zhanyong Li, R. Lee Penn, Omar K. Farha, Joseph T. Hupp, Andreas Stein, and Connie C. Lu, Faraday Discussions (2017), vol. 201, 299-314.

Electron Mobility and Trapping in Ferrihydrite Nanoparticles, Jennifer A. Soltis, Adam M. Schwartzberg, Piotr Zarzycki, R. Lee Penn, Kevin M. Rosso, and Benjamin Gilbert, ACS Earth Space Chem. (2017), vol 1(4), 216-226.

Effect of nonreactive kaolinite on 4-chloronitrobenzene reduction by Fe(II) in goethite-kaolinite heterogeneous suspensions, Strehlau, J.H., J.D. Schultz, A.M. Vindedahl, W.A. Arnold, and R.L. Penn, Environmental Science-Nano, (2017) 4, 325-334.

Accessible reactive surface area and abiotic redox reactivity of iron oxyhydroxides in acidic brines, Strehlau, J.H., B.M. Toner, W.A. Arnold, and R.L. Penn, Geochimica Et Cosmochimica Acta, (2017) 197, 345-355.

Quantifying Protein Concentrations Using Smartphone Colorimetry: A New Method for an Established Test, Gee, C.T., Kehoe, E., Pomerantz, W.C.K., and Penn, R.L., Journal of Chemical Education, (2017) DOI: 10.1021/acs.jchemed.6b00676.

Oriented attachment and non-classical formation in iron oxides. Penn, R. L.; Li, D.; Soltis, J. A., In Iron Oxides: From Nature to Applications, Faivre, D., Ed. (Wiley-VCH, Weinheim); (2016) p 350.

Quantifying Gold Nanoparticle Concentration in a Dietary Supplement Using Smartphone Colorimetry and Google Applications, Campos, A.R., C.M. Knutson, T.R. Knutson, A.R. Mozzetti, C.L. Haynes, and R.L. Penn, Journal of Chemical Education, (2016) 93, 318-321.

Nucleation of FAU and LTA Zeolites from Heterogeneous Aluminosilicate Precursors, Oleksiak, M.D., J.A. Soltis, M.T. Conato, R.L. Penn, and J.D. Rimer, Chemistry of Materials, (2016) 28, 4906-4916.

Selective removal of Cu2-x(S,Se) phases from Cu2ZnSn(S,Se)(4) thin films, Pinto, A.H., S.W. Shin, E.S. Aydil, and R.L. Penn, Green Chemistry, (2016) 18, 5814-5821.

A kinetic model for two-step phase transformation of hydrothermally treated nanocrystalline anatase, Sabyrov, K. and R.L. Penn, Crystengcomm, (2016) 18, 3033-3039.

Phase Transformation and Particle-Mediated Growth in the Formation of Hematite from 2-Line Ferrihydrite, Soltis, J.A., J.M. Feinberg, B. Gilbert, and R.L. Penn, Crystal Growth & Design, (2016) 16, 922-932.

Facet-Dependent Oxidative Goethite Growth As a Function of Aqueous Solution Conditions, Strehlau, J.H., M.S. Stemig, R.L. Penn, and W.A. Arnold, Environmental Science & Technology, (2016) 50, 10406-10412.

Installing Heterobimetallic Cobalt-Aluminum Single Sites on a Metal Organic Framework Support, Thompson, A.B., D.R. Pahis, V. Bernales, L.C. Gallington, C.D. Malonzo, T. Webber, S.J. Tereniak, T.C. Wang, S.P. Desai, Z.Y. Li, I.S. Kim, L. Gagliardi, R.L. Penn, K.W. Chapman, A. Stein, O.K. Farha, J.T. Hupp, A.B.F. Martinson, and C.C. Lu, Chemistry of Materials, (2016) 28, 6753-6762.

Thermal Stabilization of Metal–Organic Framework-Derived Single-Site Catalytic Clusters Through Nanocasting, Malonzo, C.; Shaker, S.; Ren, L.; Prinslow, S.; Platero-Prats, A.; Borycz, J.; Thompson, A.; Wang, T.; Farha, O.; Hupp, J.; Lu, C.; Chapman, K.; Myers, J.; Penn, R. L.; Gagliardi, L.; Tsapatsis, M.; Stein, A.; (2016). Journal of the American Chemical Society, accepted.

Character of Humic Substances as a Predictor for Goethite Nanoparticle Reactivity and Aggregation, Vindedahl AM, Stemig MS, Arnold WA, Penn RL.( 2016) Environmental Science and Technology, 50(3):1200-8. doi: 10.1021/acs.est.5b04136.

Cation-Dependent Hierarchical Assembly of U60 Nanoclusters into Macro-Ion Assemblies Imaged via Cryogenic Transmission Electron Microscopy, Soltis, J. A.; Wallace, C. M.; Penn, R. L.; Burns, P. C., (2016) Journal of the American Chemical Society, 138, pp. 191-198.

Evaluation of magnetic heating of asymmetric magnetite particles, Yao, X.; Sabyrov, K.; Klein, T.; Penn, R. L.; Wiedmann, T. S., (2015) Journal of Magnetism and Magnetic Materials, 381, pp. 21-27.

Impact of Pahokee Peat humic acid and buffer identity on goethite aggregation and reactivity, Vindedahl, A. M.; Arnold, W. A.; Penn, R. L., (2015) Environmental Science: Nano, 2, pp. 509-517.

A Fresh Look at the Crystal Violet Lab with Handheld Camera Colorimetry, Theodore R. Knutson, Cassandra M. Knutson, Abbie R. Mozzetti, Antonio R. Campos, Christy L. Haynes, and R. Lee Penn. (2015) Journal of Chemical Education, DOI: 10.1021/ed500876y.

Interface-mediated phase transformation in nanocrystalline particles: the case of the TiO2 allotropes, Sabyrov, K. & Penn, R. L. (2015) Crystengcomm, 17, 2062-2069.

Evaluation of magnetic heating of asymmetric magnetite particles, Yao, X., Sabyrov, K., Klein, T., Penn, R. L. & Wiedmann, T. S. (2015) Journal of Magnetism and Magnetic Materials, 381, 21-27.

Goethite nanoparticle aggregation: effects of buffers, metal ions, and 4-chloronitrobenzene reduction, Stemig, A. M., Do, T.A., Yuwono, V. M., Arnold, W. A. & Penn, R. L. (2014) Environmental Science-Nano, 1, 478-487.

Simple and Efficient Separation of Magnetic Minerals from Speleothems and Other Carbonates, Strehlau, J. H., Hegner, L. A., Strauss, B. E., Feinberg, J. M. & Penn, R. L. (2014) Journal of Sedimentary Research, 84, 1096-1106.

Nanocrystal growth via oriented attachment, Zhang, H., Penn, R. L., Lin, Z. & Coelfen, H. (2014) Crystengcomm, 16, 1407-1408.

Synthesis of Cu2ZnSnS4 thin films directly onto conductive substrates via selective thermolysis using microwave energy, T. Ryan Knutson, Parker J. Hanson, Eray S. Aydil, and R. Lee Penn (2014) Chem. Commun., 50(44):5902-4. doi: 10.1039/c3cc49207a.

Crystalline Nanoparticle Aggregation in Non-Aqueous Solvents, Nathan D. Burrows, Ellina Kesselman, Kairat Sabyrov, Amanda Stemig, Yeshayahu Talmon, and R. Lee Penn (2014) Cryst. Eng. Comm., 16, 1472-1481.

Two-Step Phase Transformation of Anatase to Rutile in Aqueous Suspension, Kairat Sabyrov, Vanessa Adamson, and R. Lee Penn (2014) Cryst. Eng. Comm., 16, 1488-1495.

Characterizing Crystal Growth by Oriented Aggregation, R. Lee Penn and Jennifer A. Soltis (2014) Cryst. Eng. Comm., 16, 1409-1418.

Crystal Growth by Oriented Attachment: Kinetic Models and Control Factors, Xiaogang Xue, R. Lee Penn, Edson Roberto Leite, Feng Huang, and Zhang Li, (2014) Cryst. Eng. Comm., 16, 1419-1429.

The origin of magnetic remanence in stalagmites: Observations from electron microscopy and rock magnetism, Strauss, B.E., Strehlau, J.H., Feinberg, J.M., Penn, R.L. (2013) Geochemistry, Geophysics, Geosystems, 14, 5006–5025.

Effect of pH on the Kinetics of Crystal Growth by Oriented Aggregation, Burrows, N. D.; Hale, C. R. H.; Penn, R. L., (2013) Crystal Growth & Design, 13, 3396-3403.

A disordered nanoparticle model for 6-line ferrihydrite, Gilbert, B.; Erbs, J. J.; Penn, R. L.; Petkov, V.; Spagnoli, D.; Waychunas, G. A., (2013) American Mineralogist, 98, 1465-1476.

Cryogenic Transmission Electron Microscopy: Aqueous Suspensions of Nanoscale Objects Microscopy and Microanalysis, Nathan D Burrows and R Lee Penn (2013), Microscopy and Microanalysis, DOI:10.1017/S1431927613013354.

Introducing Colorimetric Analysis with Camera Phones and Digital Cameras: An Activity for High School or General Chemistry, Kehoe, E.; Penn, R. L., (2013) Journal of Chemical Education, 90, 1191–1195.

Size-Dependent Anatase to Rutile Phase Transformation and Particle Growth, Kairat Sabyrov, Nathan D. Burrows, and R. Lee Penn (2013) Chemistry of Materials, 25, 1408-1415 DOI: 10.1021/cm302129a.

Aggregation of ferrihydrite nanoparticles in aqueous systems, Virany M. Yuwono, Nathan D. Burrows, Jennifer A. Soltis, Tram Anh Do, and R. Lee Penn (2012) Faraday Discussions, in press.

Effect of Ionic Strength on the Kinetics of Crystal Growth by Oriented Aggregation, Nathan D. Burrows, Christopher R. H. Hale, and R. Lee Penn (2012) Crystal Growth and Design, DOI: 10.1021/cg3004849 Article ASAP.

X-ray magnetic circular dichroism provides strong evidence for tetrahedral iron in ferrihydrite, Guyodo, Yohan; Sainctavit, Philippe; Arrio, Marie-Anne; et al. (2012) Geochemistry Geophysics Geosystems, 13 Q06Z44 DOI: 10.1029/2012GC004182.

On the nucleation and crystallization of silicalite-1 from a dilute clear sol, Kumar, S.; Penn, R. L.; Tsapatsis, M. (2011) Microporous and Mesoporous Materials, 144 (1-3), 74-81.

Size-Dependent Bandgap of Nanogoethite, Zhang, H.; Bayne, M.; Fernando, S.; Legg, B.; Zhu, M.; Penn, R. L.; Banfield, J. F. (2011) Journal of Physical Chemistry C, 115 (36), 17704-17710.

Controlling heterogenite particle morphology and microstructure by varying synthetic conditions, Jason C. Myers, R. Lee Penn (2011) Materials Research Bulletin, 46(5), 649-657.

Sub-40 nm Zeolite Suspensions via Disassembly of Three-Dimensionally Ordered Mesoporous-Imprinted Silicalite-1, P.S. Lee, X.Y. Zhang, J.A. Stoeger, A. Malek, W. Fan, S. Kumar, W.C. Yoo, S. Al Hashimi, R.L. Penn, A. Stein, M.Tsapatsis (2011) Journal of the American Chemical Society, 133, 493-502.

Separation, characterization and initial reaction studies of magnetite particles from Hanford sediments, D. R. Baer, A. E. Grosz, E. S. Ilton, K. M. Krupka, J. Liu, R. L. Penn, and A. Pepin (2010), Physics and Chemistry of the Earth, 35, 233-241.

Tracking Surface Evolution Using Ligand-Assisted Dissolution of Cobalt Oxyhydroxide Jason C. Myers and R. Lee Penn (2010), Langmuir, Article ASAP.

Self-reversal of magnetization in oceanic submarine basalts studied with XMCD, Carvallo, C., P. Sainctavit, M.-A. Arrio, Y. Guyodo, R. L. Penn, B. Forsberg, A. Rogalev, F. Wilhelm, and A. Smekhova (2010) Geophys. Res. Lett., 37, L11306, doi:10.1029/2010GL043390.

Characterization and Reactivity of Iron Nanoparticles prepared with added Cu, Pd, and Ni, Chan Lan Chun, Donald R. Baer, Dean W. Matson, James E. Amonette and R. Lee Penn (2010) Environ. Sci. Technol., 2010, 44 (13), pp 5079–5085.

Chemical Transformations during Aging of Zerovalent Iron Nanoparticles in the Presence of Common Groundwater Dissolved Constituents, Brian C. Reinsch, Brady Forsberg, R. Lee Penn, Christopher S. Kim and Gregory V. Lowry (2010) Environ. Sci. Technol., 2010, 44 (9), pp 3455–3461.

Oriented Aggregation: Formation and Transformation of Mesocrystal Intermediates Revealed, Yuwono, VM; Burrows, ND; Soltis JA; and Penn, RL (2010) Journal of the American Chemical Society, ASAP publication date 29 January 2010.

Quantifying the Kinetics of Crystal Growth by Oriented Aggregation, Burrows, ND; Yuwono, VM; and Penn, RL (2010) Materials Research Society Bulletin, 35, 133-137 (invited and peer reviewed review article in a special issue titled "Lessons from Nature--Biomimetic Approaches to Minerals with Complex Structures") .

Reductive Dissolution of Arsenic-Bearing Ferrihydrite, Erbs, JJ; Berquó, TS; Reinsch, BC; Lowry, GV; Banerjee, SK; and Penn, RL (2010) Geochimica et Cosmochimica Acta, 74, 3382-3395.

Effects of magnetic interactions in antiferromagnetic ferrihydrite particles, Berquo, TS; Erbs, JJ; Lindquist, A; Penn, RL; Banerjee, SK (2009) Journal of Physics-Condensed Matter, 21: DI 10.1088/0953-8984/21/17/176005.

Influence of Ionic Strength, pH, and Cation Valence on Aggregation Kinetics of Titanium Dioxide Nanoparticles, French, RA; Jacobson, AR; Kim, B; Isley, SL; Penn, RL; Baveye, PC (2009) Environmental Science and Technology, 43: 1354-1359.

Zinc oxide nanoparticle growth from homogenous solution: Influence of Zn:OH, water concentration, and surfactant additives, Ratkovich, A; Penn, RL (2009) Materials Research Bulletin, 44: 993-998.

Growth Patterns and Shape Development of Zeolite Nanocrystals in Confined Syntheses, Yoo, WC; Kumar, S; Penn, RL; Tsapatsis, M; Stein, A (2009) Journal of the American Chemical Society, 131: 12377-12383.

Titanium Dioxide Nanoparticles: Impact of Increasing Ionic Strength During Synthesis, Reflux and, Hydrothermal Aging, S. L. Isley, David S. Jordan, and R. L. Penn (2009), Materials Research Bulletin, 44: 119-125.

Influence of Size on Reductive Dissolution of Six-Line Ferrihydrite, Jasmine J. Erbs, Benjamin Gilbert, and R. Lee Penn (2008), Journal of Physical Chemistry C, 112: 12127-12133.

A Structural Resolution Cryo-TEM Study of the Early Stages of MFI Growth, Sandeep Kumar, Zhuopeng Wang, R. Lee Penn, and Michael Tsapatsis (2008), Journal of the American Chemical Society, 130(51): 17284-17286.

Nanoscale reactor engineering: hydrothermal synthesis of uniform zeolite particles in massively parallel reaction chambers, Won Cheol Yoo, Sandeep Kumar, Zhiyong Wang, Nicholas S. Ergang, Wei Fan,; Georgios N. Karanikolos, Alon V. McCormick, R. Lee Penn, Michael Tsapatsis, and Andreas Stein, (2008) Angewandte Chemie, International Edition, 47(47): 9096-9099.

Hierarchical nanofabrication of microporous crystals with ordered mesoporosity Wei Fan, Mark A. Snyder, Sandeep Kumar, Pyung-Soo Lee, Won Cheol Yoo, Alon V. McCormick, R.Lee Penn, Andreas Stein, and Michael Tsapatsis, (2008) Nature Materials, 7(12): 984-991.

Aging of iron nanoparticles in water: Effects on structure and reactivity. In International Environmental Nanotechnology Conference: Applications and Implications, Tratnyek, P., G.; Sarathy, V.; Nurmi, J. T.; Baer, D. R.; Amonette, J. E.; Chun, C. L.; Penn, R. L.; Reardon, E. J., (7-9 October 2008), Chicago, IL, U.S. Environmental Protection Agency, 2009, Vol. EPA 905-R09-032, pp. 193-196 (peer reviewed proceedings).

Tuning the properties of iron nanoparticles: Doping effects on reactivity and aging. In International Environmental Nanotechnology Conference: Applications and Implications Baer, D. R.; Tratnyek, P. G.; Amonette, J. E.; Chun, C. L.; Nachimuthu, P.; Nurmi, J. T.; Penn, R. L.; Matson, D. W.; Linehan, J. C.; Qiang, Y.; Sharma, A., (7-9 October 2008), Chicago, IL, U.S. Environmental Protection Agency, 2009, Vol. EPA 905-R09-032, pp. 73-78 (peer reviewed proceedings).

Controlling Oriented Aggregation using Increasing Reagent Concentrations and Trihalo Acetic Acid Surfactants, A. S. Ratkovich and R. L. Penn (2008), Journal of Solid State Chemistry, 181: 1600-1608.

Zinc Oxide Nanoparticle Growth from Homogenous Solution: Influence of Zn:OH, Water Concentration, and Surfactant Additives, A. S. Ratkovich and R. L. Penn, in press with the Materials Research Bulletin.

Titanium Dioxide Nanoparticles: Effect of Sol-Gel pH on Phase Composition, Particle Size, and Particle Growth Mechanism, S. L. Isley and R. L. Penn (2008), Journal of Physical Chemistry C, 112, 4469-4474.

Nanominerals, Mineral Nanoparticles, and Earth Chemistry. Michael F. Hochella, Jr., Steven K. Lower, Patricia A. Maurice, R. Lee Penn, Nita Sahai, Donald L. Sparks, Benjamin S. Twining (2008), Science, 319: 1631-1635.

Aging of iron nanoparticles in aqueous solution: Effects on structure and reactivity. Sarathy, Vaishnavi, Tratnyek, Paul G, Nurmi, James T., Baer, Donald R., Amonette, James E., Chun, Chan Lan, Penn, R. Lee, Reardon, Eric J. (2008), Journal of Physical Chemistry C, 112: 2286-2293

Layer structure preservation during swelling, pillaring, and exfoliation of a zeolite precursor. Maheshwari, Sudeep, Jordan, Edgar, Kumar, Sandeep, Bates, Frank S., Penn, R. Lee, Shantz, Daniel F., Tsapatsis, Michael (2008). Journal of the American Chemical Society, 130: 1507-1516.

Controlling Nanosized ZnO Growth Kinetics using Various Zn:OH Concentration Ratios.  A. S. Ratkovich and R. L. Penn (2007), Journal of Physical Chemistry C., 111: 14098-14104.

Size Dependent Kinetics of Oriented Aggregation.  R. L. Penn, K. Tanaka, and J. J. Erbs (2007), Journal of Crystal Growth, 309: 97-102.

Resolving an elusive structure. R. L. Penn (2007), Science, 316:1704-5.

Evolving Surface Reactivity of Cobalt Oxyhydroxide Nanoparticles. J. C. Myers and R. L. Penn (2007) Journal of Physical Chemistry C, 111: 10597-10602.

Influence of Aluminum Substitution on the Reactivity of Magnetite Nanoparticles. T. Jentzsch, C.L. Chun, R. S. Gabor, and R. L. Penn (2007), Journal of Physical Chemistry C, 111:10247-10253.

High Crystallinity Si-Ferrihydrite:  An Insight into its Néel Temperature and Size Dependence of Magnetic properties.  T. S. Berquó, S. K. Banerjee, R. G. Ford, R. L. Penn, and T. Pichler (2007), Journal of Geophysical Research, 112:B02102/1-B02102/12.

Aggregative Growth of Silicalite-1.  S. Kumar, T. M. Davis, H. Ramanan, R. L. Penn, and M. Tsapatsis (2007), Journal of Physical Chemistry B, 111:3398-3403.

The Adsorption of Perfluorooctane Sulfonate onto Sand, Clay, and Iron Oxide Surfaces.  R. L. Johnson, A. J. Anschutz, J. M. Smolen, M. F. Simcik, and R. L. Penn (2007), Journal of Chemical & Engineering Data, 52:1156-1161.

Influence of Ionic Strength on Brookite Content in Sol-Gel Synthesized Titania before and after Hydrothermal Aging.  S. L. Isley, E. R. Anderson, and R. L. Penn (2006), Electrochemical Society Transactions, 9:37.

Controlled growth of alpha-FeOOH nanorods by exploiting oriented aggregation. R. Lee Penn, J. Erbs, and D. Gulliver, (2006).  Journal of Cyrstal Growth, 293:1-4.

Rock Magnetic, Chemical, and Bacterial Community Analysis of a Modern Soil from Nebraska.  Y. Guyodo, T. M. LaPara, Amy J. Anschutz, R. L. Penn, , S. K. Banerjee, C. E. Geiss, and W. Zanner (2006), Earth and Planetary Science Letters 251: 168-178

Relative Brookite and Anatase Content in Sol-Gel Synthesized Titanium Dioxide Nanoparticles. Sara Isley and R. Lee Penn, Journal of Physical Chemistry B, 110:15134-15139.

Influence of Aluminum Doping on Ferrihydrite Nanoparticle Reactivity. Teresa Jentzsch and R. Lee Penn (2006), Journal of Physical Chemistry B, 110:3299-3304.

Kinetic and Microscopic Studies of Reductive Transformations of Organic Contaminants on Goethite. C. L. Chun, R. L. Penn, and W. A. Arnold (2006), Environmental Science and Technology, 40: 3299-3304.

Magnetic Properties of Synthetic Six-Line Ferrihydrite Nanoparticles.  Y. Guyodo, S. K. Banerjee, R. L. Penn, D. J. Burleson, T. S. Berquo, T. Seda, and P. Solheid (2006), Physics of the Earth and Planetary Interior, special issue on “Developments in Techniques and Methods Related to Rock Magnetism,” 154:  222-233.

Mechanistic Principles of Nanoparticle Evolution to Zeolite Crystals. T. M. Davis, T. O. Drews, H. Ramanan, C. He, H. Schnablegger, M. A. Katsoulakis, E. Kokkoli, R. L. Penn, and M. Tsapatsis (2006), Nature Materials, 5: 400-408.

Building a Successful Middle School Outreach Effort: Microscopy Camp 2005. R. L. Penn, L. Flynn, and P. Johnson. Journal of Chemical Education (accepted - expected publication date is early 2007 - please feel invited to request a pre-print by email).

Magnetic Properties of Synthetic Six-Line Ferrihydrite Nanoparticles. Y. Guyodo, S. K. Banerjee, R. L. Penn, D. J. Burleson, T. S. Berquo, T. Seda, and P. Solheid (2006), Physics of the Earth and Planetary Interior special issue on “Developments in Techniques and Methods Related to Rock Magnetism,” 154: 222-233.

Two-Step Growth of Goethite from Ferrihydrite. D. J. Burleson and R. L. Penn (2006), Langmuir; 22:402-409.

Reduction of Crystalline Iron (III) Oxyhydroxides Using Hydroquinone: Influence of Phase and Particle Size. A. J. Anschutz and R. L. Penn (2005), Geochemical Transactions, 6:60-66.

On the Characterization of Environmental Nanoparticles. D. J. Burleson, M. D. Driessen, and R. L. Penn (2004) an invited review article for the Journal of Environmental Science and Health Part A, A39:2707-2753. (invited and peer-reviewed article)

Characterization and Properties of Metallic Iron Nanoparticles: Spectroscopy, Electrochemistry, and Kinetics. J. T. Nurmi, P. G. Tratnyek, V. Sarathy, D. R. Baer, J. E. Amonette, K. H. Pecher, C. Wang, J. C. Linehan, D. W. Matson, R. L. Penn, and M. D. Driessen (2005) Nanoscale Environmental Science and Technology Issue of Environmental Science and Technology, 39:1221-1230.

Kinetics of Oriented Aggregation. R. L. Penn (2004) Journal of Physical Chemistry B, 108:12707-12712.

From Nanodots to Nanorods: Oriented Aggregation and Magnetic Evolution of Nanocrystalline Goethite. Y. Guyodo, A. Mostrom, R. L. Penn, and S. K. Banerjee (2003) Geophysical Research Letters, 30, 19-1 - 19-4.

The Growth Kinetics of TiO2 Nanoparticles from Titanium(IV) Alkoxide at High Water/Titanium Ratio. G. Oskam, A. Nellore, R. L. Penn, and P. C. Searson (2003) Journal of Physical Chemistry B, 107, 1734-1738.

The Influence of Anion on the Coarsening Kinetics of ZnO nanoparticles. Z. S. Hu, G. Oskam, R. L. Penn, N. Pesika, and P. C. Searson (2003) Journal of Physical Chemistry B, 107, 3124-3130.

Coarsening of metal oxide nanoparticles. G. Oskam, Z. S. Hu, R. L. Penn, N. Pesika, and P. C. Searson (2002) Physical Review E, 66, art. no. 011403 (4 pages).

Epitaxial Assembly in Aged Colloids. R. L. Penn, G. Oskam, T. J. Strathmann, P. C. Searson, A. T. Stone, and D. R. Veblen (2001) Journal of Physical Chemistry, B, 105, 2177-2182.

Defects and disorder: Probing the surface chemistry of heterogenite (CoOOH) by dissolution using hydroquinone and iminodiacetic acid. R. L. Penn, A. T. Stone, and D. R. Veblen (2001) Journal of Physical Chemistry, 105, 4690-4697.

"Iron Oxide" Coatings on Sand Grains from the Atlantic Coastal Plain: HRTEM Characterization. R. L. Penn, C. Zhu, H. Xu, and D. R. Veblen (2001) Geology, 29, 843–846.

Condensation and Commentary of "Discrete Atom Imaging of One-Dimensional Crystals Formed Within Single-Walled Carbon Nanotubes" by R. R. Meyer et al., (2000) Science 289, 1324-1326; CHEMTRACTS -- Inorganic Chemistry, volume 13, pages 825-827.

Preferential dissolution along misoriented boundaries in heterogenite. R. L. Penn, A. T. Stone, D. R. Veblen. In the Materials Research Society Proceedings for SYMPOSIUM M: Morphology and Dynamics of Crystal Surfaces in Complex Molecular Systems, in press.

Exchange Coupling in Epitaxial CoO/NiFe Bilayers with Compensated and Uncompensated Interfacial Spin Structures. N. J. Gökemeijer, R. L. Penn, D. R. Veblen, and C. L. Chien, Physical Review, B, 63 (17): art. no. 174422, May, 2001.

Aggregation-based crystal growth and microstructure development in natural iron oxyhydroxide biomineralization products. J.F. Banfield, S.A. Welch, H.Z. Zhang, T.T. Ebert, R.L. Penn (2000) Science, 289, 751-754.

Imperfect oriented attachment: Dislocation generation in defect-free nanocrystals. J. F. Banfield and R. L. Penn (1998) Science, 281, 969-971.

The anatase to rutile phase transformation: Nucleation at {112} anatase twin boundaries. R. L. Penn and J. F. Banfield (1999) American Mineralogist, 84, 871-876.

Morphology development and crystal growth in nanocrystalline aggregates under hydrothermal conditions: Insights from titania. R.L. Penn and J.F. Banfield (1999) Geochimica et Cosmochimica Acta, 63, 1549-1557.

Oriented attachment and growth, twinning, polytypism, and formation of metastable phases: Insights from nanocrystalline TiO2. R.L. Penn and J.F. Banfield (1998) American Mineralogist, 83, 1077-1082.

Enhanced adsorption of molecules on surfaces of nanocrystalline particles.
H.Z. Zhang, R.L. Penn, R.J. Hamers, and J.F. Banfield (1999) Journal of Physical Chemistry B 103, 4656-4662.

TEM investigation of Lewiston, Idaho Fibrolite: Implications for grain boundary energetics and Al2SiO5 phase relations. R. L. Penn, J. F. Banfield, and D. M. Kerrick (1999) American Mineralogist, 84, 152-159.

Synthesis of nanocrystalline Barium Hexaferrite from nanocrystalline goethite using the hydrothermal method. R. L. Penn, J. F. Banfield, J. Voigt; Proceedings of the 1996 Spring Meeting of the Materials Research Society SYMPOSIUM S: Aqueous Chemistry and Geochemistry of Oxides, Oxyhydroxides, and Related Materials, 432, 175-181.

Mechanical properties of metals: Experiments with steel, copper, tin, zinc, and soap bubbles. M. Geselbracht, A. Ellis, R. Penn, and G. Lisensky (1994) Journal of Chemical Education, 71, 254-61.

Periodic properties in a family of common semiconductors: Experiment with light emitting diodes. G. Lisensky, R. Penn, M. Geselbracht, and A. Ellis (1992) Journal of Chemical Education, 69, 151-6.

Electro-optical evidence for the chelate effect at semiconductor surfaces. G. Lisensky, R. Penn, C. Murphy, and A. Ellis (1990) Science, 248, 840-843.

photo of the Penn Research Group - summer 2017
Penn Group Summer 2017