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HXN team members, from left, Evgeny Nazaretski, Ken Lauer, Sebastian Kalbfleisch, Xiaojing Huang, Yong Chu, Nathalie Bouet and Hanfei Yan. Photo courtesy of BNL

By Daniel Dunaief

There’s precision in measurements and then there’s the world of Yong Chu. The head of a beamline that’s housed off to the side in a separate, concrete structure from similar efforts at Brookhaven National Laboratory, Chu led the design, construction and commissioning of a sophisticated beamline with a resolution of as low as 3 nanometers, which he hopes will get down to 1 nanometer within a year.

Just as a measure of contrast, a human hair is about 80,000 nanometers wide. Why so fine a resolution? For starters, seeing objects or processes at that high level can offer insights into how they function, how to improve their manufacture or how to counteract the effects of harmful processes.

With a battery, for example, the Hard X-ray Nanoprobe, or HXN beamline, could help reveal structural weaknesses in the nanostructure that could cause safety issues. In biology, numerous functions involve sub-cellular organelles that respond to proteins. Proteins are typically smaller than the HXN beamline can image, although researchers can tag the proteins with metals, which allows Chu, his colleagues and visiting scientists to see an aggregate of these proteins.

The HXN beamline can also help explore environmental problems, such as how plants transport harmful nanoparticles to their fruits or how artificial compounds absorb nuclear waste. Imaging beamlines that use micro-focused beams typically offer spatial resolution of 10 microns, 1 micron or even 100 nanometers, according to Ryan Tappero, the head scientist at the X-ray Fluorescence Microprobe at BNL, who has used the HXN for his research. Using the NSLS II source properties and a new x-ray optics development routinely offers resolution of 10 nanometers, which pushes the spatial resolution down by another factor of 10, which makes the HXN, according to Tappero, a “game changer.”

Tappero described Chu as a “rock star” and suggested he was an “exceptional beamline scientist” who is “very knowledgeable about X-ray optics.”

BNL houses 19 beamlines at the National Synchrotron Light Source II, a state-of-the-art facility large enough that scientists ride adult tricycles inside it to travel from one beamline to another and to transport supplies around the facility. BNL is building another nine beamlines that it hopes to have operational within the next 18 months. Each of these beamlines offers a different way to explore the world of matter. Some beamlines do not use a focused beam, while others produce beams with high angular or high energy resolution. Imaging beamlines such as the HXN produce a small beam size.

The HXN beamline has the highest spatial resolution of any beamline at the NSLS-II. Scientists building the HXN grew a nanofocusing lens with a dedicated deposition system that was constructed at the NSLS-II Research and Development lab. The system grew a nanofocusing lens a layer at a time, alternating materials and controlling the thickness at better than 1 nanometer, Chu explained.

The beamline where Chu works has padded walls, a door separating it from the rest of the light source and a monitor that records the temperature to the thousandths of a degree. “We are constantly monitoring the temperature around the X-ray microscope and inside of the X-ray microscope chamber,” he said. Around the microscope, he can keep the temperature stable within 0.03 degree Celsius. In the chamber, the scientists maintain the temperature at better than 0.003 degree Celsius.

So, now that Chu and his colleagues built their beamline, have the scientists come? Indeed, the interest in using the HXN has been well above the available time slots. For the three cycles each year, BNL receives about four requests for each available time. This reflects the unique qualities of the instrument, Chu said, adding that he doesn’t expect the rate to drop considerably, even as the HXN continues to operate, because of the ongoing demand.

Researchers have to go through a peer review process, where their ideas are graded for the likelihood of success and for the opportunity to learn from the experiments. All beam time proposals are reviewed by external expert panels, which examine the scientific merit, appropriateness of use of the facility, capability of proposers and quality of prior performance and the research plan and technical feasibility.

Chu fields about 10 calls per month from scientists who want to speak with him about the feasibility of their ideas. He may suggest another station at the NSLS-II or at the Advanced Photon Source at Argonne National Laboratory in Chicago, where he was a beamline scientist starting in 1999.

“I know many of the beamlines” at the Advanced Photon Source, he said. “I recommend some of the potential users to perform experiments at the APS first before coming to the HXN.” By the time scientists arrive at his beamline, Chu said he’s gotten to know them through numerous discussions. He considers them “as a guest” at the HXN hotel. “We try to make sure the experimental needs for the users are met as much as possible,” he said.

The HXN beamline has three staff scientists and two postdoctoral fellows who remain in contact with scientists who use the facility. “For most of the users, at least one of us is working throughout the weekends and late evenings,” said Chu.

Not just a staff scientist, Chu is also a user of the HXN, with currently one active general user proposal through a peer review process in which he is collaborating with Stony Brook University and BNL scientist Esther Takeuchi to explore the nanostructure of metal atoms during phase separation in batteries.

Chu and his wife Youngkyu Park, who works at Cold Spring Harbor Laboratory as a research investigator in basic and preclinical cancer research, live in Northport. The couple’s 22-year-old son Luke is attending Nassau Community College and is planning to transfer to Stony Brook this fall to study engineering. Their daughter Joyce is 18 and is enrolled in the Parsons School of Design in New York.

Chu grew up in Seoul, South Korea, and came to the United States when he was 18. He attended Caltech. While Chu’s parents wanted him to become a doctor, he was more inspired by a cartoon called Astro Boy, in which a scientist, Dr. Tenma, is a hero solving problems. As for the work of the scientists who visit his beamline, Chu said the “success of individual users is the success of the beamline.”

From left, BNL Staff Scientist Lihua Zhang, former postdoctoral researcher Vitor Manfrinato and BNL Senior Scientist Aaron Stein. Photo courtesy of BNL

By Daniel Dunaief

It took a village to build this particular village or, more precisely, a pattern so small it could fit thousands of times over on the head of a pin.

Working at Brookhaven National Laboratory’s Center for Functional Nanomaterials, a team of researchers wanted to exceed the boundaries of creating small patterns with finely honed features. The group included Aaron Stein, a senior scientist at CFN, Charles Black, the head of CFN, Vitor Manfrinato, a former postdoctoral researcher at BNL and several other key members of the BNL team. The team added a pattern generator that allowed them to control a microscope to create a pattern that set a record for drawing at the 1-nanometer scale.

Just for reference, the width of a human hair is about 80,000 to 100,000 nanometers. The size of the pattern is a breakthrough as standard tools and processes generally produce patterns on a scale of 10 nanometers. “We were able to push that by a factor of five or 10 below,” Stein said. “When you get to those small size scales, that’s pretty significant.”

In this case, the novelty that enabled this resolution originated with the idea of employing the scanning transmission electron microscope, which isn’t typically used for patterning to create these images. The scanning transmission electron microscope has an extraordinarily high resolution, while the pattern generator allowed them to control the patterns they drew and other aspects of the exposure.

Researchers at CFN are focusing on this spectacularly small world to manipulate properties such as chemical reactivity, electrical conductivity and light interactions. “This new development is exciting because it will allow other researchers to create nanomaterials at previously impossible size scales,” Kevin Yager, a group leader at CFN explained in an email. “There are numerous predictions about how materials should behave differently at a size scale at 1 to 3 nanometers. With this patterning capability, we can finally test some of those hypotheses,” he said.

Stein and the research team were able to create this pattern on a simple polymer, polymethyl methacrylate, or PMMA for short. “It’s surprising to us that you don’t need fancy materials to create these kinds of features,” said Stein. “PMMA is a common polymer. It’s Plexiglas. It’s kind of exciting to do something that is beyond what people have done” up until now.

One of the many possible next steps, now that the researchers have developed this proof of principle, is to apply this technique to a substance that might have commercial use. Taking the same approach with silicon, for example, could lead to innovations in electronics. “We can make them with a high clarity of patterns and sharp corners, which we can’t do with other techniques,” Stein said.

The BNL research team would “like to apply this to real world research,” which could include electronics and transistors, as well as photonics and plasmonics, he added. This project arose out of a doctoral thesis that Manfrinato was conducting. He is one of the many scientists who came to BNL, which isa Department of Energy funded user facility that provides tools to conduct research for scientists from around the world.

Manfrinato was a doctoral student in Professor Karl Berggren’s group at the Massachusetts Institute of Technology. In an email, Manfrinato explained that he was interested in pushing the resolution limits of e-beam lithography. “BNL has state of the art facilities and expert staff, so our collaboration was a great fit, starting in 2011,” he explained.

Other scientists thought it was worthwhile to continue to pursue this effort, encouraging him to “come here and work on this. It’s a home grown project,” Stein said. Manfrinato worked on his doctorate from 2011 to 2015, at which point he became a postdoctoral researcher at BNL. His efforts involved several groups, all within the Center for Functional Nanomaterials at BNL. Stein, Manfrinato and Black worked on the lithography part of the project, while Lihua Zhang and Eric Stach developed the microscopy. Yager helped the team to understand the processes by which they could pattern PMMA at such small scale lengths.

“No one or two of us could have made this happen,” Stein said. “That’s really the joy of working in a place like this: There are [so many] permutations for collaborating.” Indeed, the other scientists involved in this study were Yager; Zhang, a staff scientist in electron microscopy; Stach, the electron microscopy group leader at CFN; and Chang-Yong Nam, who assisted with the pattern transfer.

Manfrinato, who is now a research and development engineer at a startup company in the San Francisco Bay area, explained that this lithographic technique has numerous possible applications. Other researchers could create prototypes of their devices at a level below the 10-nanometer scale at CFN. Manfrinato interacts with the BNL team a few times a month and he has “exciting results to be further analyzed, explored and published,” he wrote in an email.

Stein said BNL would like to offer this patterning device for other users who come to BNL. Ultimately, researchers use materials at this scale to find properties that may vary when the materials are larger. Sometimes, the properties such as color, chemical reactivity, electrical conductivity and light interactions change enough to create opportunities for new products, innovations or more efficient designs.

A resident of Huntington, Stein and his wife Sasha Abraham, who works in the planning department for the Town of Huntington, have a 15-year-old daughter Lily and a 13-year-old son Henry.

As for his work, Stein said he’s interested in continuing to push the limits of understanding various properties of nanomaterials. “My career has been using the e-beam lithography to make all sorts of structures,” he said. “We’re in a regime where people have not been there before. Finding the bottom is very interesting. Figuring out the limits of this technique is, in and of itself” an incredible opportunity.

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