Doctors have been using X-rays to examine their patients’ bones since the late 1800s, taking advantage of what was then a fledgling technology that could record only the most basic pictures.
Coherent optical radiation, which arrived in the 1960s with the invention of the laser, allowed for far better imaging but still had its limits.
Today’s next-generation coherent X-ray sources are far more advanced, providing spatial resolution that would have been incomprehensible just a decade ago, allowing researchers to see, for the first time, “the ultra-small world.”
“This technology can lead to discoveries in nearly every field of science.” — Linda Young, Argonne Distinguished Fellow
“Coherent X-rays help us extract more information from exceedingly complex, amorphous systems — right down to the atomic level,” said Linda Young, an Argonne Distinguished Fellow and a leader in the field of atomic, molecular and optical physics.
Young’s initial work was funded through the U.S. Department of Energy’s Argonne National Laboratory’s Laboratory Directed Research and Development (LDRD) Program, which provides seed money to grow the laboratory’s research in new directions, supporting high-risk, potentially high-reward research and development.
“It’s pretty remarkable. This technology can lead to discoveries in nearly every field of science,” Young said.
Supratik Guha, Argonne’s Senior Science Adviser, and Director of the Center for Nanoscale Materials at Argonne, said the funding helps support out-of-the-box type experimentation. “LDRD funding is one way that national labs can explore new areas that might steer their future research directions,” he said.
Vivian Sullivan, LDRD program manager at Argonne, said it is critical to the lab’s success.
“Without that freedom to explore, we would end up stagnating,” she said.
Young is using the LDRD funding to push the limits of coherent X-rays.
“The dream is to take a single molecule — it can have 1 million atoms in it — put it into the X-ray laser beam and image its 3-D architecture with atomic-scale resolution and simultaneously watch intricate movements on a quadrillionth of a second timescale,” she said.
LDRD is funding two related projects under Young’s leadership. The first allows researchers to examine the transformation of a small particle made up of two different types of atoms from one structure into another structure, akin to converting graphite into diamond.
“You can do that with pressure,” Young said. “When you apply pressure — that is, squeezing something — you can change the structure of the object. The original structure, like graphite, for example, is in in one phase and the new structure, such as say diamond, is in another phase, hence the term pressure-induced phase transition.”
Young said that scientists are trying to determine what moves first — the electrons or the nuclei.
“We can do that now because the X-rays can monitor the changes in the electronic structure and nuclear structure simultaneously,” she said.
Such a breakthrough would help scientists better understand numerous processes that occur via coordinated electron — including nuclear motions, such as photosynthesis, and also explore methods to create novel materials by design.
In another study, Young is using the very strong electromagnetic fields from optical lasers to rip an electron from its nucleus.
“This is the process we are looking at in water,” she said. “If you pull an electron off water, you are left with H2O plus or ionized water. We can’t see it happening using optical or UV radiation, but it leaves a distinctive signature in the X-ray region. This type of research will have implications for radiation chemistry and radiation damage.”
In order to do either project, one needs to use the world’s most advanced coherent X-ray sources, which can be found at the laboratory.
“This is an incredible place to do this type of work,” Young said. “The expertise and equipment here is truly astounding.”
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