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University of Delaware’s Surface Analysis Facility is home to a
new time-of-flight secondary ion mass spectrometer. The instrument
offers critical techniques for understanding surface composition and
reactivity across chemistry, material science, environmental science,
chemical engineering, conservation science and physics.
Editor’s note: An open house is planned at the University of Delaware’s Surface Analysis Facility,
located in Lammot du Pont Laboratory on UD’s Newark campus Friday,
Sept. 23, from noon to 2 p.m. The event will display a newly-acquired
instrument called a time-of-flight secondary ion mass spectrometer,
which can detect surface materials at the atomic level. People on campus
and in the wider community can look at the new device and others in the
The University of Delaware’s chemical detection capabilities gained
some extra-powerful research muscle recently, with the acquisition of a
time-of-flight secondary ion mass spectrometer (ToF-SIMS).
The instrument was purchased from ION-TOF USA, Inc., a leading
electronics manufacturing company. The purchase was made possible
through funding from the National Science Foundation, and it will enable
faculty, researchers and students to rapidly analyze the surface of a
sample and detect precisely what it’s made of and its reactivity. It’s
the kind of information that can help advance research relevant to
nanotechnology and materials design, catalysis, solar, cultural
heritage, microplastics and more.
ToF-SIMS mass spectrometry uses a pulsed ion beam to remove the
outermost layer of a sample. It’s not like scraping a layer of paint
from a piece of furniture, though.
“Basically, you shoot high-energy clusters of ions at the surface of a
material sample and look at the ions that are coming off. This is
different from conventional mass spectrometry, and it allows researchers
to have an extremely high-resolution look at, for example, biological
samples, plastics and even solid films,” said Andrew Teplyakov,
professor of chemistry and biochemistry, who led the proposal that
brought the instrument to UD.
It is a critical technique needed to understand surface composition
and reactivity across chemistry, material science, environmental
science, chemical engineering, conservation science and physics. Before
its arrival, no other instrument like it was available to researchers in
the state of Delaware.
Move this whole section up, swapping places with the section above it.
The new ToF-SIMS mass spectrometer shoots high-energy clusters of
ions at the surface of a material sample and records information about
the secondary ions that come off the sample. This provides extremely
high-resolution chemical and molecular information that researchers can
use in their work.
The instrument can analyze chemical information from the original
surface in the parts-per-million range. It is like detecting a single
defective tile among those covering the entire sports complex at UD. It
also has the capability to reveal the distribution of elements and
molecules on a surface with a lateral resolution down to 70 nanometers,
about 1,000 times smaller than a human hair. This resolution is higher
than any optical microscope can provide.
Additionally, ToF-SIMS provides researchers the ability to construct a
3D depth profile of materials at a depth resolution better than one
nanometer. For a simple comparison, if the diameter of a marble was one
nanometer, then the diameter of our planet would be about one meter.
This is essential when working with interfaces.
“My field is surface functionalization and surface chemistry,”
Teplyakov said. “My research group focuses on applications for making or
controlling molecules at the surface and interfaces between materials.
We’re talking about applications where entire devices could be 400 times
smaller than a human hair. If you're making a sensor based on a certain
material, having this extremely high-resolution surface and in-depth
chemical information that’s accurate down to about one billionth of a
meter is critical. This is pretty much the only selective technique that
can do this.”
Among his projects, Teplyakov’s research group will use this
instrument to illuminate how organic molecules bond at a solid surface.
He also plans to investigate why and how solar cells degrade to develop
ways to make solar technology last longer. Understanding where defects
occur could be key — and the ToF-SIMS instrument can provide this
Jocelyn Alcántara-García, associate professor in art conservation
with a joint appointment in chemistry and biochemistry, as well as at
Winterthur Museum’s Scientific Research and Analysis laboratory, is
excited to apply the ToF-SIMS to explore how colored historical textiles
decay and why some substances applied as part of conservation methods
fail, aging and degrading much like the materials they are meant to
preserve. Part of studying dyed textiles requires extracting the dye or
color molecules, called chromophores, through sampling. Some of these
extraction techniques are aggressive and can destroy the fragile color
molecules, while others are so mild that the extractions are incomplete
and require larger-than-wanted samples.
Jocelyn Alcántara-García is using results from analyses of
historical textiles from the late 18th – early 19th c. Norwich, United
Kingdom, to develop surrogate materials for testing dye mixture trends
in her work. These surrogate materials are based on findings from
Norwich worsted textiles, like the ones in this pattern book (c.
1790–1793), accession number 65 x 695.3 Winterthur Museum, Garden and
Library. UD’s time-of-flight instrument can advance this work by
providing detailed information about how color molecules bind to textile
TOF-SIMS will help us to learn how color molecules chemically bond to
textile fibers, leading to more efficient extraction procedures from
smaller samples,” said Alcántara-García.
Alcántara-García also is eager to understand how historical
materials, such as dyed textiles, painted surfaces and coatings were
made to drive better methods for studying and preserving material
“Studying textiles at different stages of deterioration can help us
see, for example, which bond is more prone to a specific type of
degradation, say light sensitivity. This would be central for display
and storage decisions,” she said.
The instrument will enable the work of over 25 research groups on campus.
For instance, for researchers developing microelectronics
technologies, the ability to analyze a sample’s depth profile will
provide atomic-scale knowledge to advance the creation of very precise
and repeatable materials, information useful for design processes or
equipment manufacturing. Meanwhile, extreme close-ups of biological
devices, films, microfluidic channels and more could one day enable
next-generation nanosystems, such as those used in biomedical device
interfaces for cardiac stimulation and mapping devices, cochlear and
retinal implants, or brain-machine interfaces.
It also could help researchers better understand microplastics,
problematic particles found in various states of repair in the ocean and
other waterways. Each microplastic particle degrades at a different
rate, so having chemical information about the surface of different
samples will provide important clues about what’s happening to the
material at different stages and how that affects the surrounding
Access to this highly sophisticated instrumentation, such as the
new time-of-flight secondary ion mass spectrometer, provides unique
training opportunities for students that can help set them apart in the
From undergraduate students to postdoctoral fellows, access to this
highly sophisticated instrumentation provides unique training
opportunities that can help set them apart in the job market.
“There are not many opportunities for students to gain hands-on
experience on these highly-sought instruments in the country. Here at
UD, we are proud to offer comprehensive operation training and practical
courses to our students at various levels to enrich their skillset in
analytical chemistry,” said Xu Feng, director of the Surface Analysis
Facility. “As the U.S. works to bring back the manufacturing of
semiconductors, it’s a huge boost to get them noticed in the job market
of microelectronics and semiconductors.”
This includes students involved in two UD Research Experience for
Undergraduate (REU) programs: the REU program for students with
disabilities and a recently established REU program for undergraduate
students from South America.
“Normally REU students come to UD for a reasonably short period of
time. The expectation that you can have a result, or maybe even a paper,
after a few months’ work … that’s exciting and attractive to students,”
This figure shows the type of depth profile that is possible with
the time-of-flight secondary ion mass spectrometer. On the left is a
graph depicting the distribution and depth of the individual elements at
the interface between a two-nanometer titanium dioxide film and a
silicon wafer. The image on the right is a 3D reconstruction of the
uniformity of this film over the surface. This information can help
researchers investigate films and surface features of just a few atomic
The ToF-SIMS complements a suite of other contemporary instruments in the Surface Analysis Facility, including an atomic force-Raman microscope (AFM-Raman) to help researchers acquire topographical information about materials and an X-ray photoelectron spectrometer
for securing molecular information on solid surfaces. Having these
highly complementary techniques available in one laboratory allows
researchers to be strategic in considering what information they want to
“With these three instruments, we now have a first-rate surface
analysis capability to support new lines of academic research and
attract industrial collaborators,” said Teplyakov.
Already, the new instrument has drawn inquiries and interest from
local companies interested in analyzing samples, including Chemours, Air
Liquide, DuPont and others. Feng and his staff, meanwhile, are standing
by to help with these inquiries and discuss possible research
“We warmly welcome researchers within and beyond the university to
come in and enjoy these top-notch surface analysis techniques,” Feng
Article by Karen B. Roberts; Photos by Evan Krape and courtesy of Jocelyn Alcántara-García and Xu Feng Published September 22, 2022