Heavy Elements and Separation Sciences
The Heavy Elements and Separation Sciences group (HESS) seeks to understand the fundamental drivers within two broad research thrusts: (i) developing a detailed mechanistic understanding of liquid-liquid separations as the process used to extract, isolate and purify the actinides, lanthanides, and their fission products, and (ii) understanding chemical trends within the 5f series and how they integrate and inform similar studies across the periodic table. In both areas we characterize solution speciation, interfacial interactions, and solid-state structures with the accuracies necessary to obtain a predictive knowledge of the energetics and multi-scale phase-transfer reactions.
Our research primarily focuses on the actinide elements, specifically those heavier than uranium. Because so little is known about their chemistry, our efforts include a significant component devoted to the synthesis and characterization of new actinide compounds. We seek to use insights gained on the unique structural and electronic properties of these heavy elements and their compounds to broadly inform trends across the entire periodic table.
Our staff works in an environment that affords rich opportunities and extensive facilities to perform state-of-the-art research on actinide elements. Available is an inventory of selected isotopes spanning Th-Cm. All of these elements are radioactive and studies of them are performed in a suite of laboratories purpose-built to provide a safe environment for transuranic sample preparation and characterization. These laboratories house the hoods, glove-boxes, dry-boxes, furnaces and associated infrastructure necessary for the synthesis of a wide variety of inorganic, alpha-emitting, actinide-containing samples, from tracer-level to the microscopic and macroscopic scale. Structure-characterization capabilities include two Bruker single-crystal diffractometers equipped with APEX II CCD detectors. Our laboratories also contain a full array of standard radioanalytical-counting equipment, electrochemical workstations, Raman, conventional UV-visible/near-IR and Fourier transform IR spectrophotometers and a SQUID magnetometer. Our laser laboratory enables a wide variety of absorption, emission, and dynamic studies of the optical response of radioactive samples from 1.5 K to 1373 K. New to this capability is recently-purchased sum-frequency-generation (SFG) equipment, acquired to underpin our program on SX interfaces.
Opportunities are afforded to our program by the co-location, at Argonne, of the Advanced Photon Source (APS) and our hot laboratories. These complementary facilities provide us with a means of characterizing the atomic structure and morphology as well as selected electronic and magnetic properties of our materials. The location of APS at Argonne permits us to measure actinide-containing samples with minimal time and effort lost to sample transport and to perform in situ chemistry on surfaces and under electrochemical control.