Andrew G Stack

Group Leader, Geochemistry & Interfacial Sciences

Andrew G. Stack focuses on understanding how minerals form and react with their surrounding solutions. He is the PI of the Basic Energy Sciences Geosciences project at ORNL, entitled "Atomic- to Pore-Scale Geochemical Processes."

Professional Activities and Service

Member, U.S. Department of Energy, Office of Science, Basic Energy Sciences Advisory Committee (2019-present); Chair, Committee of Visitors (2020), U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences and Biosciences Division

Faculty Member, Bredesen Center for Interdisciplinary Research and Graduate Education, University Tennessee/Oak Ridge National Laboratory (2016-present)

Member, American Chemical Society National Award Selection Committee (2021), Officer, ACS Geochemistry Division: Past Division Chair (2015), Division Chair (2014), Program Chair (2013), Program-Chair Elect (2012), Awards Committee Member (2016-2018).  Organizer of Geochemistry Division Programming at National American Chemical Society conferences (fall 2013, spring 2014)

Editorial Board Member, Geochemical Transactions (2013-present)

Member of ORNL Committees: Research Conflict of Interest Advisory Committee (2015-2021); Laboratory Directed Research and Development Internal Review Committee, “Next-Generation Techniques and Methods for Neutron Sciences” (2015-2017); Center for Accelerated Materials Modeling Advisory Committee (2015-2016)

Community Workshop Participation

Co-Chair: Subsurface and Geoscience breakout session, AI Town Hall for Science, Lawrence Berkeley National Laboratory (2019)

Panelist and Liaison to the Workshop Chair for the Experts’ Workshop on Carbon Capture, Utilization and Storage for the Mission Innovation Challenge global initiative (2017)

Panelist for Department of Energy, Basic Energy Sciences workshop and contributor to factual document on Basic Research Needs for the Energy-Water Nexus (2017)

Panelist/Roundtable Expert for Department of Energy, Basic Energy Sciences workshops and contributor to report on Subsurface Technology and Engineering Research Program (SubTER) and a new Grand Challenge for Subsurface Science (2015)

Awards

Outstanding Contributions to Geosciences Research Award (2014). U.S. DOE Basic Energy Sciences, Geosciences Program Award for One of Top 14 Technical Presentations (out of > 300), Twelfth Annual Conference on Carbon Capture, Utilization & Sequestration. Pittsburgh, PA, May 13-16, 2013 Profile featured at ORNL web-site: Part I, Part II and STEM Magazine (2015).Profile featured in American Chemical Society’s College-To-Career web-site.Finalist for Asylum Research AFM Image Contest
Award for One of Top 14 Technical Presentations (out of > 300), Twelfth Annual Conference on Carbon Capture, Utilization & Sequestration. Pittsburgh, PA, May 13-16, 2013
Profile featured at ORNL website: Part I, Part II and STEM Magazine (2015).
Profile featured in American Chemical Society’s College-To-Career website.
Finalist for Asylum Research AFM Image Contest

Facilities

SNS, HFIR, OIC, NERSC, APS, ALS, CNMS, etc.

Neutrons help us understand the structure and dynamics of many systems that are sometimes hard to characterize, such as liquids and amorphous solids. The swirling colors represent solutions rapidly mixed together to precipitate an amorphous solid (balls-and-sticks). Its atomic structure can be revealed by neutron diffraction, where the pulsed beam is shown in white. Image Credit: ORNL/Jill Hemman  Elements, Volume 17, No. 3 

From Stack et al., 2021 (Elements, 17, 169-174):  Neutron scattering is a powerful tool to elucidate the structure and dynamics of systems that are important to geochemists, including ion association in complex aqueous solutions, solvent-exchange reactions at mineral–water interfaces, and reaction and transport of fluids in nanoporous materials. This article focusses on three techniques: neutron diffraction, which can reveal the atomic-level structure of aqueous solutions and solids; quasi-elastic neutron scattering, which measures the diffusional dynamics at mineral–water interfaces; and small-angle neutron scattering, which can show how properties of nanoporous systems change during gas, liquid, and solute imbibition and reaction. The usefulness and applicability of the experimental results are extended by rigorous comparison to computational simulations.