Radiochemistry Annex

EMSL’s Radiochemistry Annex is designed to accelerate scientific discovery and deepen the understanding of the chemical fate and transport of radionuclides in terrestrial and subsurface ecosystems.

The annex offers experimental and computational tools uniquely suited for actinide chemistry studies. The spectroscopic and imaging instruments at this facility are ideally designed for the study of contaminated environmental materials, examination of radionuclide speciation and detection of chemical signatures. The annex houses nuclear magnetic resonance instruments and surface science capabilities, such as X-ray photoelectron spectroscopy, electron microscopy, electron microprobe, transmission electron microscopy and scanning electron microscopy. Annex users also have access to expert computational, modeling and simulation resources and support.

The annex is an environment where multiple experimental approaches are encouraged. Investigating problems at an integrated, cross-disciplinary level encourages holistic understanding, which ultimately provides policy makers the information they need to make sound remediation choices.

Like all of EMSL's capabilities, those housed in the annex are available to the scientific community at typically no cost for openly published research. Scientists gain access to instruments and collaborate with onsite microscopy experts through a peer-reviewed proposal process. Research conducted in the annex requires special information and handling. Prior to submitting a proposal, potential users should familiarize themselves with the guidance for using and shipping radioactive material to the annex.

Radiochemistry Annex videos on EMSL's YouTube channel - Learn about the individual instruments in the Radiochemistry Annex and specifically how they advance subsurface and terrestrial ecosystem science.

And don't miss the virtual tour of our Radiochemistry Annex.

Instruments

Research applications Samples containing paramagnetics Soils (SOM and NOM) Metal oxide materials for catalysis applications Researchers may operate...
Custodian(s): Nancy Washton, Sarah D Burton
EMSL's Bruker wide-bore 750 MHz solids/liquids/imaging spectrometer is dedicated to radiological and environmental samples. Housed in the EMSL...
Custodian(s): Nancy Washton
The Bruker EMX electron paramagnetic resonance (EPR) spectrometer performs continuous-wave magnetic resonance using electron spins to selectively...
Custodian(s): Eric Walter
EMSL's Digital Instruments Radiological BioScope™ Atomic Force Microscope (AFM) allows radiological samples to be examined in fluids or air with...
Custodian(s): Kevin M. Rosso
Housed in EMSL's Radiochemistry Annex, the field emission electron microprobe (EMP) enables chemical analysis and imaging of radionuclides with high...
Custodian(s): Bruce Arey

Science Highlights

Posted: July 06, 2011
Scientists from Pacific Northwest National Laboratory and Rai Enviro-Chem, LLC, recently published first-ever results that illustrate the importance...

EMSL’s Radiochemistry Annex is designed to accelerate scientific discovery and deepen the understanding of the chemical fate and transport of radionuclides in terrestrial and subsurface ecosystems.

The annex offers experimental and computational tools uniquely suited for actinide chemistry studies. The spectroscopic and imaging instruments at this facility are ideally designed for the study of contaminated environmental materials, examination of radionuclide speciation and detection of chemical signatures. The annex houses nuclear magnetic resonance instruments and surface science capabilities, such as X-ray photoelectron spectroscopy, electron microscopy, electron microprobe, transmission electron microscopy and scanning electron microscopy. Annex users also have access to expert computational, modeling and simulation resources and support.

The annex is an environment where multiple experimental approaches are encouraged. Investigating problems at an integrated, cross-disciplinary level encourages holistic understanding, which ultimately provides policy makers the information they need to make sound remediation choices.

Like all of EMSL's capabilities, those housed in the annex are available to the scientific community at typically no cost for openly published research. Scientists gain access to instruments and collaborate with onsite microscopy experts through a peer-reviewed proposal process. Research conducted in the annex requires special information and handling. Prior to submitting a proposal, potential users should familiarize themselves with the guidance for using and shipping radioactive material to the annex.

Radiochemistry Annex videos on EMSL's YouTube channel - Learn about the individual instruments in the Radiochemistry Annex and specifically how they advance subsurface and terrestrial ecosystem science.

And don't miss the virtual tour of our Radiochemistry Annex.

Ab Initio Thermodynamic Model for Magnesium Carbonates and Hydrates.

Abstract: 

An ab initio thermodynamic framework for predicting properties of hydrated magnesium carbonate minerals has been developed using density-functional theory linked to macroscopic thermodynamics through the experimental chemical potentials for MgO, water, and CO2. Including semiempirical dispersion via the Grimme method and small corrections to the generalized gradient approximation of Perdew, Burke, and Ernzerhof for the heat of formation yields a model with quantitative agreement for the benchmark minerals brucite, magnesite, nesquehonite, and hydromagnesite. The model shows how small differences in experimental conditions determine whether nesquehonite, hydromagnesite, or magnesite is the result of laboratory synthesis from carbonation of brucite, and what transformations are expected to occur on geological time scales. Because of the reliance on parameter-free first principles methods, the model is reliably extensible to experimental conditions not readily accessible to experiment and to any mineral composition for which the structure is known or can be hypothesized, including structures containing defects, substitutions, or transitional structures during solid state transformations induced by temperature changes or processes such as water, CO2, or O2 diffusion. Demonstrated applications of the ab initio thermodynamic framework include an independent means to evaluate differences in thermodynamic data for lansfordite, predicting the properties of Mg analogs of Ca-based hydrated carbonates monohydrocalcite and ikaite which have not been observed in nature, and an estimation of the thermodynamics of barringtonite from the stoichiometry and a single experimental observation.

Citation: 
Chaka AM, and AR Felmy.2014."Ab Initio Thermodynamic Model for Magnesium Carbonates and Hydrates."Journal of Physical Chemistry A 118(35):7469-7488. doi:10.1021/jp500271n
Authors: 
AM Chaka
AR Felmy
Instruments: 
Volume: 
118
Issue: 
35
Pages: 
7469-7488
Publication year: 
2014

Direct Evidence of Lithium-Induced Atomic Ordering in Amorphous TiO2 Nanotubes .

Abstract: 

In this paper, we report the first direct chemical and imaging evidence of lithium-induced atomic ordering in amorphous TiO2 nanomaterials and propose new reaction mechanisms that contradict the many works in the published literature on the lithiation behavior of these materials. The lithiation process was conducted in situ inside an atomic resolution transmission electron microscope. Our results indicate that the lithiation started with the valence reduction of Ti4+ to Ti3+ leading to a LixTiO2 intercalation compound. The continued intercalation of Li ions in TiO2 nanotubes triggered an amorphous to crystalline phase transformation. The crystals were formed as nano-islands and identified to be Li2Ti2O4 with cubic structure (a = 8.375 Å). The tendency for the formation of these crystals was verified with density functional theory (DFT) simulations. The size of the crystalline islands provides a characteristic length scale (∼5 nm) at which the atomic bonding configuration has been changed within a short time period. This phase transformation is associated with local inhomogeneities in Li distribution. On the basis of these observations, a new reaction mechanism is proposed to explain the first cycle lithiation behavior in amorphous TiO2 nanotubes.

Citation: 
Gao Q, M Gu, A Nie, F Mashayek, CM Wang, GM Odegard, and R Shahbazian-Yassar.2014."Direct Evidence of Lithium-Induced Atomic Ordering in Amorphous TiO2 Nanotubes ."Chemistry of Materials 26(4):1660-1669. doi:10.1021/cm403951b
Authors: 
Q Gao
M Gu
A Nie
F Mashayek
CM Wang
GM Odegard
R Shahbazian-Yassar
Instruments: 
Volume: 
26
Issue: 
4
Pages: 
1660-1669
Publication year: 
2014

In Situ Observation of Directed Nanoparticle Aggregation During the Synthesis of Ordered Nanoporous Metal in Soft Templates.

Abstract: 

The prevalent approach to developing new nanomaterials is a trial-and-error process of iteratively altering synthesis procedures and then characterizing the resulting nanostructures. This is fundamentally limited in that the growth processes that occur during synthesis can be inferred only from the final synthetic structure. Directly observing real-time nanomaterial growth provides unprecedented insight into the relationship between synthesis conditions and product evolution and facilitates a mechanistic approach to nanomaterial development. Here, we use in situ liquid-stage scanning transmission electron microscopy to observe the growth of mesoporous palladium in a solvated block copolymer (BCP) template under various synthesis conditions, and we ultimately determined a refined synthesis procedure that yields extended structures with ordered pores. We found that after sufficient drying time of the casting solvent (tetrahydrofuran, THF), the BCP assembles into a rigid, cylindrical micelle array with a high degree of short-range order but poor long-range order. Upon slowing the THF evaporation rate using a solvent-vapor anneal step, the long-range order was greatly improved. The electron beam induces nucleation of small particles in the aqueous phase around the micelles. The small particles then flocculate and grow into denser structures that surround, but do not overgrow, the micelles, forming an ordered mesoporous structure. The microscope observations revealed that pore disorder can be addressed prior to metal reduction and is not invariably induced by the Pd growth process itself, allowing for more rapid optimization of the synthetic method.

Citation: 
Parent LR, DB Robinson, PJ Cappillino, RJ Hartnett, P Abellan, JE Evans, ND Browning, and I Arslan.2014."In Situ Observation of Directed Nanoparticle Aggregation During the Synthesis of Ordered Nanoporous Metal in Soft Templates."Chemistry of Materials 26(3):1426-1433. doi:10.1021/cm4035209
Authors: 
LR Parent
DB Robinson
PJ Cappillino
RJ Hartnett
P Abellan
JE Evans
ND Browning
I Arslan
Instruments: 
Volume: 
26
Issue: 
3
Pages: 
1426-1433
Publication year: 
2014

Angular Distribution and Recoil Effect for 1 MeV Au+ Ions through a Si3N4 Thin Foil .

Abstract: 

The Stopping and Range of Ions in Matter (SRIM) code has been widely used to predict nuclear stopping power and angular distribution of ion-solid collisions. However, experimental validation of the predictions is insufficient for slow heavy ions in nonmetallic compounds. In this work, time-of-flight secondary ion mass spectrometry (ToF-SIMS) is applied to determine the angular distribution of 1 MeV Au ions after penetrating a Si3N4 foil with a thickness of ~100 nm. The exiting Au ions are collected by a Si wafer located ~14 mm behind the Si3N4 foil, and the resulting 2-dimensional distribution of Au ions on the Si wafer is measured by ToF-SIMS. The SRIM-predicted angular distribution of Au ions through the Si3N4 thin foil is compared with the measured results, indicating that SRIM slightly overestimates the nuclear stopping power by up to 10%. In addition, thickness reduction of the suspended Si3N4 foils induced by 1 MeV Au ion irradiation is observed with an average loss rate of ~107 atom/ion.

Citation: 
Jin K, Z Zhu, S Manandhar, J Liu, CH Chen, V Shutthanandan, S Thevuthasan, WJ Weber, and Y Zhang.2014."Angular Distribution and Recoil Effect for 1 MeV Au+ Ions through a Si3N4 Thin Foil ."Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms 332:346-350. doi:10.1016/j.nimb.2014.02.093
Authors: 
K Jin
Z Zhu
S Manhar
J Liu
CH Chen
V Shutthanan
S Thevuthasan
WJ Weber
Y Zhang
Volume: 
Issue: 
Pages: 
Publication year: 
2014

Assessment of Controlling Processes for Field-Scale Uranium Reactive Transport under Highly Transient Flow Conditions.

Abstract: 

This paper presents the results of a comprehensive model-based analysis of a uranium tracer test conducted at the U.S Department of Energy Hanford 300 Area (300A) IFRC site. A three-dimensional multi-component reactive transport model was employed to assess the key factors and processes that control the field-scale uranium reactive transport. Taking into consideration of relevant physical and chemical processes, the selected conceptual/numerical model replicates the spatial and temporal variations of the observed U(VI) concentrations reasonably well in spite of the highly complex field conditions. A sensitivity analysis was performed to interrogate the relative importance of various processes and factors for reactive transport of U(VI) at the field-scale. The results indicate that multi-rate U(VI) sorption/desorption, U(VI) surface complexation reactions, and initial U(VI) concentrations were the most important processes and factors controlling U(VI) migration. On the other hand, cation exchange reactions, the choice of the surface complexation model, and dual-domain mass transfer processes, which were previously identified to be important in laboratory experiments, played less important roles under the field-scale experimental condition at the 300A site. However, the model simulations also revealed that the groundwater chemistry was relatively stable during the uranium tracer experiment and therefore presumably not dynamic enough to appropriately assess the effects of ion exchange reaction and the choice of surface complexation models on U(VI) sorption and desorption. Furthermore, it also showed that the field experimental duration (16 days) was not sufficiently long to precisely assess the role of a majority of the sorption sites that were accessed by slow kinetic processes within the dual domain model. The sensitivity analysis revealed the crucial role of the intraborehole flow that occurred within the long-screened monitoring wells and thus significantly affected both field-scale measurements and simulated U(VI) concentrations as a combined effect of aquifer heterogeneity and highly dynamic flow conditions. Overall, this study, which provides one of the few detailed and highly data-constrained uranium transport simulations, highlights the difference in controlling processes between laboratory and field scale that prevent a simple direct upscaling of laboratory-scale models.

Citation: 
Ma R, C Zheng, C Liu, J Greskowiak, H Prommer, and JM Zachara.2014."Assessment of Controlling Processes for Field-Scale Uranium Reactive Transport under Highly Transient Flow Conditions."Water Resources Research 50(2):1006-1024. doi:10.1002/2013WR013835
Authors: 
Ma R
C Zheng
C Liu
J Greskowiak
H Prommer
JM Zachara
Instruments: 
Volume: 
50
Issue: 
2
Pages: 
1006-1024
Publication year: 
2014

Atomic-level studies of the depletion in reactive sites during clay mineral dissolution.

Abstract: 

Environmental weathering is typically viewed as a macroscopic phenomenon that is based on a number of competing atomic- or molecular-level processes. One important process is the release of metal or metalloid elements into solution at the water-rock interface. To both explain and predict environmental weathering, the atomic-level “reactive sites” on the surfaces of minerals must be characterized and quantified. Whether these sites are atomic in nature, represented by a chemical bond, or comprise a more complex assemblage of covalently or ionically linked atoms or molecules, the kinetic rate of atomic release (dissolution) depends on the available reactive surface. For one important class of materials, clay minerals, their reactive surface areas are a challenge to quantify as it is well recognized that there are two distinct types of surfaces: edge sites and basal planes1-3. Clay dissolution rates continuously decrease over time as reactive edge sites are preferentially depleted4. Changes in reactive surface area and the difficulties in quantifying this elusive variable have often been cited as one key reason for the complexity in developing accurate rate equations3,5,6. In this work, we demonstrate a solid-state nuclear magnetic resonance (SSNMR) method for counting the number of reactive surface sites on a defined quantity of a clay mineral. Using this SSNMR proxy7-9, changes in reactive surface area were monitored for a series of batch dissolution experiments of low-defect kaolinite KGa-1b at 21 ºC and pH 3 over the course of 80 days. While no changes (within error) were observed for specific surface area (as determined from BET gas isotherm data), the SSNMR proxy revealed decreases in the number of reactive surface sites per gram of kaolinite as a function of dissolution time. This observation can be tied to a concomitant decrease in the rates of release of Si and Al into solution. These results further highlight the need to account for changes in reactive surface area when developing and using dissolution rate models for clay minerals and other heterogeneous materials in the environment.

Citation: 
Sanders RL, NM Washton, and KT Mueller.2012."Atomic-level studies of the depletion in reactive sites during clay mineral dissolution."Geochimica et Cosmochimica Acta 92:100-116. doi:10.1016/j.gca.2012.05.038
Authors: 
RL Sers
NM Washton
KT Mueller
Volume: 
Issue: 
Pages: 
Publication year: 
2012

Enhanced Quantum Efficiency From Hybrid Cesium Halide/Copper Photocathode.

Abstract: 

The quantum efficiency of Cu is found to increase dramatically when coated by a CsI film and then irradiated by a UV laser. Over three orders of magnitude quantum efficiency enhancement at 266 nm is observed in CsI/Cu(100), indicating potential application in future photocathode devices. Upon laser irradiation, a large work function reduction to a value less than 2 eV is also observed, significantly greater than for similarly treated CsBr/Cu(100). The initial QE enhancement, prior to laser irradiation, is attributed to interface interaction, surface cleanliness and the intrinsic properties of the Cs halide film. Further QE enhancement following activation is attributed to formation of inter-band states and Cs metal accumulation at the interface induced by laser irradiation.

Citation: 
Kong L, AG Joly, TC Droubay, Y Gong, and WP Hess.2014."Enhanced Quantum Efficiency From Hybrid Cesium Halide/Copper Photocathode."Applied Physics Letters 104(17):Article No. 171106. doi:10.1063/1.4874339
Authors: 
L Kong
AG Joly
TC Droubay
Y Gong
WP Hess
Instruments: 
Volume: 
Issue: 
Pages: 
Publication year: 
2014

Molecular Structure and Stability of Dissolved Lithium Polysulfide Species.

Abstract: 

Ability to predict the solubility and stability of lithium polysulfide is vital in realizing longer lasting lithium-sulfur batteries. Herein we report a combined computational and experimental spectroscopic analysis to understand the dissolution mechanism of lithium polysulfide species in an aprotic solvent medium. Multinuclear NMR and sulfur K-edge X-ray absorption (XAS) analysis reveals that the lithium exchange between polysulfide species and solvent molecule constitutes the first step in the dissolution process. Lithium exchange leads to de-lithiated polysulfide ions which subsequently forms highly reactive free radicals through disproportion reaction. The energy required for the disproportion and possible dimer formation reactions of the polysulfide species are analyzed using density functional theory (DFT) calculations. We validate our calculations with variable temperature electron spin resonance (ESR) measurements. Based on these findings, we discuss approaches to optimize the electrolyte in order to control the polysulfide solubility. The energy required for the disproportion and possible dimer formation reactions of the polysulfide species are analyzed using density functional theory (DFT) calculations. We validate our calculations with variable temperature electron spin resonance (ESR) measurements. Based on these findings, we discuss approaches to optimize the electrolyte in order to control the polysulfide solubility.

Citation: 
Vijayakumar M, N Govind, ED Walter, SD Burton, AK Shukla, A Devaraj, J Xiao, J Liu, CM Wang, AM Karim, and S Thevuthasan.2014."Molecular Structure and Stability of Dissolved Lithium Polysulfide Species."Physical Chemistry Chemical Physics. PCCP 16(22):10923-10932. doi:10.1039/c4cp00889H
Authors: 
M Vijayakumar
N Govind
ED Walter
SD Burton
AK Shukla
A Devaraj
J Xiao
J Liu
CM Wang
AM Karim
S Thevuthasan
Instruments: 
Volume: 
16
Issue: 
22
Pages: 
10923-10932
Publication year: 
2014

Methanol Synthesis from CO2 Hydrogenation over a Pd4/In2O3 Model Catalyst: A Combined DFT and Kinetic Study.

Abstract: 

Methanol synthesis from CO2 hydrogenation on Pd4/In2O3 has been investigated using density functional theory (DFT) and microkinetic modeling. In this study, three possible routes in the reaction network of CO2 + H2 → CH3OH + H2O have been examined. Our DFT results show that the HCOO route competes with the RWGS route whereas a high activation barrier kinetically blocks the HCOOH route. DFT results also suggest that H2COO* + H* ↔ H2CO* +OH* and cis-COOH* + H* ↔CO* + H2O* are the rate limiting steps in the HCOO route and the RWGS route, respectively. Microkinetic modeling results demonstrate that the HCOO route is the dominant reaction route for methanol synthesis from CO2 hydrogenation. We found that the activation of H adatom on the small Pd cluster and the presence of H2O on the In2O3 substrate play important roles in promoting the methanol synthesis. The hydroxyl adsorbed at the interface of Pd4/In2O3 induces the transformation of the supported Pd4 cluster from a butterfly structure into a tetrahedron structure. This important structure change not only indicates the dynamical nature of the supported nanoparticle catalyst structure during the reaction but also shifts the final hydrogenation step from H2COH to CH3O.

Citation: 
Ye J, C Liu, D Mei, and Q Ge.2014."Methanol Synthesis from CO2 Hydrogenation over a Pd4/In2O3 Model Catalyst: A Combined DFT and Kinetic Study."Journal of Catalysis 317:44-53. doi:10.1016/j.jcat.2014.06.002
Authors: 
Ye J
C Liu
D Mei
Q Ge
Instruments: 
Volume: 
Issue: 
Pages: 
Publication year: 
2014

Mineralization of Basalts in the CO2-H2O-SO2-O2 System.

Abstract: 

Sequestering carbon dioxide (CO2) containing minor amounts of co-contaminants in geologic formations was investigated in the laboratory through the use of high pressure static experiments. Five different basalt samples were immersed in water equilibrated with supercritical CO2 containing 1wt% sulfur dioxide (SO2) and 1wt% oxygen (O2) at reservoir conditions (~100 bar, 90°C) for 49 and 98 days. Gypsum (CaSO4) was a common precipitate, occurred early as elongated blades with striations, and served as substrates for other mineral products. Bimodal pulses of water released during dehydroxylation were key indicators along with X-ray diffraction for verifying the presences of jarosite-alunite group minerals. Well-developed pseudocubic jarosite crystals formed surface coatings, and in some instances mixtures of natrojarosite and natroalunite aggregated into spherically shaped structures measuring 100 μm in diameter. Reaction products were also characterized using infrared spectroscopy, which indicated OH and Fe-O stretching modes. The presences of jarosite-alunite group minerals were found in the lower wavenumber region from 700–400 cm-1. A strong preferential incorporation of Fe(III) into natrojarosite was attributed to the oxidation potential of O2. Evidence of CO2 was detected during thermal decomposition of precipitates, suggesting the onset of mineral carbonation.

Citation: 
Schaef HT, JA Horner, AT Owen, CJ Thompson, JS Loring, and BP McGrail.2014."Mineralization of Basalts in the CO2-H2O-SO2-O2 System."Environmental Science & Technology 48(9):5298-5305. doi:10.1021/es404964j
Authors: 
HT Schaef
JA Horner
AT Owen
CJ Thompson
JS Loring
BP McGrail
Volume: 
48
Issue: 
9
Pages: 
5298-5305
Publication year: 
2014

Pages