Lensless camera uses X-rays to view nanoscale materials
and biological specimens
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ARGONNE, Ill. (Feb. 19, 2008) – X-rays have been used for decades to take
pictures of broken bones, but scientists at the U.S. Department of Energy's
(DOE) Argonne National Laboratory and their collaborators have developed
a lensless X-ray technique that can take images of ultra-small structures buried
in nanoparticles and nanomaterials, and features within whole biological
cells such as cellular nuclei.
This research was funded by the Department of Energy's Office of Basic
Energy Sciences as part of its mission to foster and support fundamental
research to expand the scientific foundations for new and improved energy
technologies, and by the National
Science Foundation. |
Argonne scientists along with scientists from the University
of California at Los Angeles, the University
of Melbourne, La
Trobe University and the
Australian
Synchrotron developed a way to examine internal and buried structures
in micrometer-sized samples on the scale of nanometers. This is important to
the understanding of how materials behave electrically, magnetically and under
thermal and mechanical stress. Application of this capability to biology and
biomedicine could contribute to our understanding of disease and its eradication,
healing after injury, cancer and cell death.
X-rays are ideally suited for nanoscale imaging because of their ability to
penetrate the interior of the object, but their resolution has traditionally
been limited by lens technology. The new lensless technique being developed
at Argonne avoids this limitation.
“There is no lens involved at all,” said Ian McNulty, the lead Argonne author
on a new publication on this work appearing in the journal Physical
Review Letters. “Instead, a computer uses sophisticated algorithms to reconstruct
the image. We expect this technique will enhance our understanding of many
problems in materials and biological research.” The technique can be extended
beyond the current resolution of about 20 nanometers to image the internal
structure of micrometer-sized samples at finer resolution, reaching deep into
the nanometer scale.
Other types of microscopes, such as electron microscopes, can image structural
details on the nanometer scale, but once the sample reaches sizes of a few
micrometers and larger, the usefulness of these instruments to probe its internal
structure is limited. In many cases, only the surface of the sample can be
studied, or the sample must be sliced to view its interior, which can be destructive.
A collaborative team comprising members of the X-ray Microscopy and Imaging
Group at Argonne's Advanced
Photon Source (APS) and a team led by Professor
John Miao at the University of California at Los Angeles developed a powerful
new extension of the new lensless imaging technique that enables high resolution
imaging of a specific element buried inside a sample.
The key is the high intensity X-ray beams created at the APS at Argonne.
An intense, coherent X-ray beam collides with the sample, creating a diffraction
pattern which is recorded by a charge coupled device (CCD) camera. The X-ray
energy is tuned to an atomic resonance of a target element in the sample. Using
sophisticated phase-recovery algorithms, a computer reconstructs an image of
the specimen that highlights the presence of the element. The result is an
image of the internal architecture of the sample at nanometer resolution and
without destructive slicing. By using X-ray energies that coincide with an
atomic absorption edge, the imaging process can distinguish between different
elements in the sample.
If the nucleus or other parts of a cell are labeled with protein specific
tags, it can be imaged within whole cells at a resolution far greater than
that of ordinary microscopes.
Another application of this new method of imaging includes the burgeoning
field of nanoengineering, which endeavors to develop more efficient catalysts
for the petrochemical and energy industries and materials with electrically
programmable mechanical, thermal and other properties.
“There are only a handful of places in the world this can be done and APS
is the only place in the United States at these X-ray energies,” X-ray Microscopy
and Imaging Group Leader Qun Shen said. “We would eventually like to create
a dedicated, permanent laboratory facility at the APS for this imaging technique
that can be used by scientists on a routine basis.”
A dedicated facility would require building an additional beamline at the
APS, which currently has 34 sectors, each containing one or more beamlines.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology.
The nation's first national laboratory, Argonne conducts leading-edge basic
and applied scientific research in virtually every scientific discipline. Argonne
researchers work closely with researchers from hundreds of companies, universities,
and federal, state and municipal agencies to help them solve their specific
problems, advance America 's scientific leadership and prepare the nation for
a better future. With employees from more than 60 nations, Argonne is managed
by UChicago
Argonne, LLC for
the U.S.
Department of Energy's Office
of Science.
For more information, please
contact Brock Cooper (630/252-5565 or media@anl.gov)
at Argonne.
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