July 7, 2020
Argonne physicist searches for new uses for X-ray lasers and ways to support junior scientists
Like many of us, physicist Linda Young is working from home these days, though her home is more unique than most. “We live in Enrico Fermi’s old house,” she said. “I always hope that I’ll breathe some inspiration from being in this house, but I’m not sure if I have.”
Whether through Fermi’s inspiration or her own scientific prowess, Young has built an impressive research career studying the interactions of X-rays with matter. She leads the Atomic, Molecular, and Optical Physics Group at Argonne National Laboratory and is a part-time professor of physics at the University of Chicago. She previously served as the head of the X-ray Science Division at Argonne, overseeing experiments at one of the world’s top X-ray sources.
X-ray interactions with matter have a long and storied history, beginning with the discovery of X-rays in 1895. Scientists harnessed this very high energy form of light to reveal unseen secrets of our world, allowing us to glimpse the bones beneath our skin and to decode the unique arrangement of atoms that make up different molecules.
In the century since the discovery of X-rays, scientists have continuously improved the strength of X-ray light sources and used them in new ways to understand the makeup of materials. These experiments took a huge leap forward ten years ago, Young said, with the development of a new type of X-ray source, the X-ray free-electron laser (XFEL).
“Now, because we have X-ray free-electron lasers, new life has been injected into the topic of X-ray interactions with matter. We suddenly can have X-ray pulses that are of very short duration, very short wavelength, and very high intensity,” said Young.
As the leader of the Atomic, Molecular, and Optical (AMO) Physics group at Argonne, Young plays an instrumental role in understanding how these X-ray lasers work and what they can be used for. “In our group, we work together to figure out how we can really utilize these super strong, coherent X-ray pulses to divine the secrets of matter,” she said.
Though Young has risen through the ranks to become an expert in X-ray physics, she began her career at Argonne with a background in a different field, optical laser spectroscopy. She integrated this knowledge into the AMO physics group’s studies of atomic structure, and in 1994, as the youngest scientist in the group, Young was promoted to group leader.
Young’s tenure as group leader coincided with the opening of the Advanced Photon Source (APS) synchrotron at Argonne, a kilometer-long electron storage ring used as a source of bright X-ray beams. To utilize the convenience and capabilities of this world-class laboratory, the group shifted its focus to X-ray science. Young hired new team members with expertise in X-ray physics and led the design of two beamlines—X-ray laboratories within APS with unique instruments and capabilities.
The AMO physics group pushed the boundaries of the study of X-rays’ interactions with matter, using facilities at the APS as well as other X-ray sources. The group’s success in the field and interest in powerful X-ray techniques led to their involvement with the first XFEL.
In October 2009, Young led the inaugural experiment at the Linac Coherent Light Source, the world’s first XFEL, built at the Stanford Linear Accelerator (SLAC). Her team demonstrated that the super intense X-ray beam could remove many electrons from an atom in a single burst, and by controlling the energy of the beam, they could eject specific groups of electrons from the atom. These experiments demonstrated an unparalleled level of power and control over the interactions of X-rays with matter.
After the success of these first XFEL experiments, many countries built XFEL light sources to expand access to this new technology. Young and her group visit these laboratories to perform experiments, and she lends her expertise at several light sources, serving on the scientific board of four international XFEL laboratories.
Young travels to international laboratories to do groundbreaking research with the world’s best scientists, but she notes that these experiences have more than just a scientific impact. “I think doing experiments at light sources around the world is very enriching. You get to have insight into different international perspectives and make friends around the globe,” she said.
X-ray scientists compete for funding and acclaim, but when they come together at international laboratories, they work as a team to tackle big problems. Their dream, Young explained, is to use XFELs to look at complex molecules in a new way. The ultra-strong, ultra-short pulses of X-ray light should allow them to take snapshots of the locations of all the atoms in a molecule as it moves around in a solution. Putting these snapshots together could create a 3D image of a huge, complicated molecule like a protein.
Young brings these ideas back to the University of Chicago, where she teaches a graduate course on X-ray physics and applications. She enjoys sharing her passion for these complex experiments with students who would not typically work with advanced X-ray techniques. As she interacts with students, she adapts her course in response to their feedback and encourages students to pursue their interests through the lens of X-ray sciences.
“I think it’s really invigorating to teach students because they’re so eager to learn, and you learn a lot of things from them,” said Young.
Young’s willingness to learn and adapt has served her well as a mentor at both Argonne and UChicago. She has mentored a number of junior scientists at Argonne, helping them make decisions about their career path and even assisting with connections for future job placements.
At UChicago, she works to make the physics department supportive of all students and serves as chair of the department’s equity, diversity, and inclusion committee. She coordinates seminars with speakers from underrepresented groups in the sciences and hosted the 2020 American Physical Society Conference for Undergraduate Women in Physics at UChicago.
Young notes that amidst the growing movement against systemic racism, she has realized that these previous activities to promote diversity in the department were not enough. The committee is currently reaching out through student-led town hall meetings and seeking feedback on how they can better support minorities in physics. In the first meeting, students requested more opportunities for mentorship, and Young is excited to mentor more students and help them achieve their goals.
As more student feedback comes in, Young is listening and ready to work for lasting change in the physics department. “I think that this is a really important time for committees to step up and really do something concrete. I am looking forward to doing whatever I can in my own way.”