Our Research
Our top publications based on synchrotron research demonstrate disciplinary breadth and worldwide impact.
Flake et al., Journal of the Electrochemical Society (2011) 158, 5, E45-E49
The direct electrochemical conversion of CO鈧� to methanol offers a promising pathway
for producing liquid fuels such as dimethyl ether and synthetic gasoline, as well
as valuable feedstocks for organic synthesis. In this work, Cu L-edge XANES spectra
were used to evaluate the performance of cuprous oxide thin films in comparison with
air-oxidized and anodized copper electrodes. The results indicate that the cuprous
oxide electrodes generate substantially higher methanol yields and efficiencies, suggesting
that Cu(I) species play a critical role in enhancing selectivity toward methanol.
Ding, Roy et al., Science (2018) 362, 6414, 560鈥�564
This paper, co-authored by Louisiana Light Source researcher Amitava Roy, appeared
in and reported a broadly applicable synthesis strategy for bimetallic nanoparticles.
Highly impactful for catalysis and materials science communities.
Kauffman et al., The Journal of Physical Chemistry C (2018) 122, 49, 27991-28000
Kauffman鈥檚 paper studied the electronic structure and local atomic environment of
the Au/Cu nanoparticles with XAS under reaction-relevant conditions, confirming alloy
formation and surface bonding characteristics influenced by thiol ligands. The results
indicated the Au/Cu nanoparticles enhanced catalytic selectivity, leading to highly
efficient conversion of CO鈧� to CO with improved activity compared to monometallic
counterparts.
Stegemann et al., Science of the Total Environment (2019) 690, November 10, 573-583
The collaborative work determined the speciation and local chemical environment of
phosphorus and associated metals in meat and bone meal and poultry litter ashes. XRD
and XAS analyses revealed that phosphorus is primarily bound within stable mineral
phases (e.g., with Ca, Fe, or Al), which affects its recoverability and highlights
the conditions necessary for efficient phosphorus extraction and bioavailability.
Xu et al., The Journal of Physical Chemistry C (2021) 125, 31, 17008鈭�17018
XAS and XPS techniques were performed to analyze the oxidation states and local chemical
environment of elements in the CoCrFeNi high-entropy alloy, revealing how the surface
oxidation changes under reaction conditions. The results showed that Ni sites remain
least oxidized and a partially oxidized HEA surface is formed under acidic hydrogen
evolution reaction conditions, leading to enhanced catalytic activity with low overpotential
compared to Pt metal.
Cook et al., Environmental Science: Processes & Impacts (2016) 18 (1), 42鈥�50
The adsorption mechanism of phenol by iron(III)-exchanged calcium montmorillonite
clay was investigated to elucidate the processes responsible for the formation of
environmentally persistent free radicals on the clay surface. XAS results revealed
that the reduction of Fe(III) to Fe(II) and the presence of iron sites facilitate
electron transfer with phenol, leading to the generation and stabilization of these
radicals.
Ding et al., Angewandte Chemie International Edition (2023) 62, 46, e202309949
Ding鈥檚 group discovered that constructing plastic鈥揷atalyst solid鈥搒olid interfaces
enables solvent-free depolymerization of polyethylene terephthalate via vapor-phase
methanolysis at relatively low temperatures. A zinc catalyst introduced through electrostatic
adsorption effectively catalyzes the process, and CAMD鈥檚 XAS beamline was used to
probe the catalyst鈥檚 surface structure and interfacial interactions.
Ma et al., The Journal of Physical Chemistry B (2022) 126, 5, 2531鈥�2541
SAXS results showed charged gold nanoparticles are absorbed inside porous surface-modified
silica particles. Depending on the pore size and salinity, different arrangements
of the NP are found. The filling of the pores affects the catalytic rate of a model
reaction with the largest pores as most active.
Hormes et al., Environmental Science & Technology (2013) 47, 9, 4375-4382
The study used synchrotron-based Pb L鈧�-edge X-ray Absorption Near Edge Spectroscopy
(XANES) to examine how lead is taken up and chemically speciated in different plant
families and a lichen. The group observed that lead enters plant roots through the
outer apoplast as either Pb虏鈦�(aq) or Pb鈧�(OH)鈧勨伌鈦�(aq), depending on soil pH and lead
concentration. The Pb L鈧�-edge XANES spectra of dried and fresh plant samples were
nearly identical, indicating that sorption remained unaffected by water removal and
was influenced primarily by the initial ionic strength. No evidence of bonding to
biologically important groups (鈥揝, 鈥揘) or precipitation as phosphate (鈥揚O鈧�) was observed.
Sprunger et al., Langmuir (2015) 31, 13, 3869-3875
Environmentally persistent free radicals (EPFRs) produce reactive oxygen species in
aqueous environments, and their introduction into living tissues can induce oxidative
stress, cell death, and heightened vulnerability to viral infections. Understanding
the fundamental mechanisms governing EPFR formation is therefore crucial for elucidating
their environmental toxicity and developing effective remediation strategies. Sprunger鈥檚
group utilized photoelectron spectroscopy and electron energy loss spectroscopy on
a well-defined model system鈥攑henol chemisorbed on TiO鈧�(110)鈥攖o directly monitor changes
in the electronic structure of both the oxide and the adsorbed phenol as a function
of adsorption temperature. The results provide strong evidence that high-temperature
exposure leads to filling of empty states in TiO鈧� and depopulation of the phenol HOMO,
consistent with the conceptual model proposed for EPFR formation.
McPeak et al., Advanced Materials (2020) 32, 23, 1906478, 1-8
Materials capable of efficient hot-carrier generation and transport in the near-infrared
(NIR) can revolutionize semiconductor technologies and advance NIR optoelectronic
devices. Alloys, unlike pure metals, exhibit emergent properties that enable new design
strategies. LSU鈥檚 Chemical Engineering Professor McPeak and his collaborators demonstrate
that a noble-transition alloy, Au鈧揚d鈧佲倠鈧�, outperforms its constituent metals in both
hot-carrier generation and lifetime under NIR excitation, owing to hybridized Au鈥揚d
d-bands near the Fermi level. Ultraviolet photoelectron spectroscopy (UPS) and X-ray
photoelectron spectroscopy (XPS) measurements at Louisiana Light Source revealed the
nature of these hybridized states. These results highlight noble-transition alloys
as promising materials for efficient, long-lived NIR hot-carrier applications.
De Mel et al., Langmuir (2021) 37, 31, 9560鈥�9570
In this work, SAXS measurements found the medically relevant acetaminophen assembles
inside the hydrophobic part of the bilayer of phospholipid vesicles, which act as
a cell membrane model system. This results in reduced membrane rigidity as proven
by NSE and a deformed shape, as observed by cryo-TEM.
Ham, Butler et al., Chemistry of Materials (2004) 16, 21, 4032鈥�4042
This paper demonstrated synchrotron X-ray tomography at multiple energies to determine
3D chemical distributions of brominated flame retardants and antimony oxide in polystyrene,
establishing Louisiana Light Source鈥檚 multi-energy CT methodology that has been applied
across materials science and environmental chemistry.
Kio, et al., Additive Manufacturing (2018) 24, 364-372
This paper, co-authored by Louisiana Light Source鈥檚 Kyungmin Ham, demonstrated X-ray
interferometry to examine 3D printed objects鈥� defects. X-ray interferometry provides
a dark-field image, essentially a small-angle X-ray scattering image, of the voids
and print defects in an additively manufactured polymer object. The interferometers
used were tuned to scattering length 2-5 渭m and configured to measure scattering along
both vertical and horizontal directions. The dark-field projection images show orientation-dependent
X-ray scattering due to anisotropic voids and gaps at the filament-to-filament interface
in fused-deposition-modeling additive manufacturing objects. The absorption and dark-field
volumes are used to correlate printhead trajectory with print defect density.
Butler et al., The Journal of Physical Chemistry B (2010) 114, 1, 2鈥�9
This work extended synchrotron X-ray tomography to measure 3D chemical distributions
of flame retardants and synergists in fiberglass-reinforced polymer blends, demonstrating
industrial materials characterization with direct relevance to fire-safety engineering.
Hormes et al., Microchemical Journal (2020) Volume 154, May, 104571
This paper investigated whether calcium X-ray Absorption Near Edge Structure (XANES)
spectra can serve as a 鈥渢hermometer鈥� to estimate the firing temperature of clays from
the UNESCO World Heritage Site of Poverty Point by analyzing how calcium鈥檚 local coordination
environment changes upon heating. Synchrotron-based XANES measurements revealed clear,
systematic variations in pre-edge and white-line features with increasing firing temperature,
providing the first direct evidence supporting the hypothesis that at least some of
the Poverty Point objects were used as cooking stones.
Nemati et al., Scientific Reports (2025) 15, 3167
This study, co-authored by Louisiana Light Source鈥檚 Kyungmin Ham, describes procedures for embedding digital information into additively manufactured components as well as procedures for readout and tensile testing. X-ray imaging, both conventional and interferometry, was explored to detect the digital information. X-ray interferometry showed increased void detectability, one advantage of loose powder. These results suggest a standard selective laser sintering printer with typical metal powders could reasonably expect to print 100 bits of embedded digital information in a gauge volume 6 mm in diameter as 300 渭m voids while still maintaining tensile specifications.