3D X-rays might be possible, says U. Nebraska professor

By Ellen Hirst, Daily Nebraskan, U. Nebraska

Intense laser physics. Sounds fun, right?

Anthony Starace, a professor of astronomy and physics at the University of Nebraska-Lincoln, has had 15 years to appreciate the joy of intense laser physics. His research at UNL, in collaboration with two Russian institutes, could contribute to the creation of X-rays that produce 3-D images, or holograms.

His research began when it was still considered an “experimental discipline.” It has uncovered essential information that, when tested in an experiment, should make 3-D X-rays possible.

“Now, we are sticking our necks out and making a prediction about something that should be observed but hasn’t yet,” he said.

With a fast enough computer, Starace said, one could theoretically create a 3-D image in real time: for example, a hologram of a human heart beating.

Coherent high-powered X-rays are the key to making this a reality. The light used to take images is incoherent, Starace said. Coherent waves would be more like water waves.

“Imagine, if you drop a stone in a lake, you get ripples,” Starace said. “If you drop another stone, the ripples overlap, and you get a pattern. That is a coherent pattern.”

For 3-D X-rays to work, one must freeze the wave properties of light.

“You have an object: You put on a special sheet of material and shine a laser light through it to freeze the wave-like properties of the light reflected by the object,” Starace said.

The ultimate goal is to create X-ray lasers that don’t yet exist – X-rays with much smaller wavelengths to project images of smaller objects.

When an X-ray is taken, a very intense light is shined on an atom, forcing electrons to oscillate. Starace’s research has shown that this process is very sensitive to the size of the atoms.

“If you choose larger atoms than typical hydrogen or helium, like xenon with atomic number 54,” Starace said, “you can get 100 times more intense X-rays.”

The possibility of 3-D imaging proteins is of particular interest in the medical field because of their complex structures.

“All biological processes are covered by proteins,” Starace said. “You have to look at the structure of the protein to determine how a given protein functions in the body. For example, if you want to know whether the protein could bind to another protein in the body, you need to know the shapes to see what it could do.”

Nanoscientists could also benefit from this possibly imminent breakthrough in technology. The director of the Nebraska Center for Materials and Nanoscience, David Sellmyer, said determining the structure of nanoscale objects is an extremely important aspect of nanoscience.

“It would help us study the structures that are only a few nanometers,” Sellmyer said. “The general aim is to understand the relationship between the actual structure and the actual properties.”

Although there are many examples of how this would be useful, Sellmyer said, it would be beneficial in the medical field.

“If you think about making nanoscale clusters or nanoparticles,” Sellmyer said, “some of those things can be steered with a magnetic field to a tumor in the body and can be used to kill the tumor. We need to understand exactly how that nanoparticle works; it might be a complex structure.”

Starace said any scientist in the world can take his information and put it to the test, actually creating this 3-D X-ray. In the meantime, he has moved on to attosecond science, a new field of physics.

As Starace now spends his days figuring out how to make laser pulses that are a billionth of a billionth of a second long, freezing oscillating electrons in their paths, the science world is one step closer to 3-D imaging of the world’s tiniest particles.

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