University Professor Dwayne Miller of the Department of Chemistry has been recognized with the 2025 Earle K. Plyler Prize for Molecular Spectroscopy & Dynamics. The prize, which may be given for experimental or theoretical achievements, a single dramatic innovation, or for a series of research contributions, recognizes Miller’s work in giving an atomic perspective on molecular reaction dynamics.
In research published in 2003, Miller was able to capture atomic motions undergoing a structural transition, using a new concept in “ultrabright” electron sources by literally lighting up atomic motions as they occurred. The source brightness improved to the point of recording the first atomically resolved molecular reaction in 2013.
Given the enormous challenges for achieving simultaneously femtosecond time resolution and atomic spatial resolution, the so called “Atomic Movie” had been thought to be an impossible dream.
“The promise of microscopy of any form is that whenever you see something at higher resolution, you learn more about it. You will see things you missed before. Think of van Leeuwenhoek’s first microscope and observation of animalcules in pond water,” said Miller. “That ultimately led to germ theory.”
"In our work, we developed ultrabright electrons sources that are literally bright enough to light up atomic motions and can follow these motions through a process called diffraction.” Miller explained that the diffraction or scattering of electrons can be directly connected to the atomic positions in a type of microscope where Fourier transforms perform the function of lenses.
"For chemistry, the highest resolution is at the atomic level. To directly observe atomic motions during the defining moments of chemistry is to observe the essence of chemistry. For even moderately small molecules there are an astronomical number of ways to rearrange the atoms. This poses the question of how chemistry scales in complexity from a few atoms up to the biological scale.”
The first atomic movies met the promise of microscopy. Miller and his group could directly observe the collapse of innumerable nuclear degrees of freedom to just a few key reaction modes.
He said, “It is mesmerizing to see the enormous simplification of chemistry to a small subset of reaction modes. Thanks to this work, we now have our first glimpses of the underlying physics responsible for localizing the forces to a few so-called reaction modes.”
“Not all atomic motions are equal. Some strongly modulate the electron density and create forces directing the chemistry. It is beautifully simple at some level and shows how spatial correlations in motions can lead to biological processes, because this same concept of spatial correlations must also operate within cells. We are seeing scaling principles in how chemistry can empower biological processes.”
Breaking the barrier to observing atomically resolved structural dynamics — achieving what many assumed to be the purest form of a gendanken experiment — opened structural and chemical dynamics to atomic level inspection. Miller’s work has thus sparked a new field in which researchers can aspire to see chemistry in action.
We can now understand how chemistry scales in complexity. Not all atomic motions are equal. Some strongly modulate the electron density and create forces directing the chemistry. It is beautifully simple, and shows how spatial correlations in motions can lead to biological processes.
What does that mean outside the laboratory?
One impact of Miller’s research is a potential revolution in surgery. Insight gained by the first atomic movie of laser driven phase transitions has led to the development of the Picosecond InfraRed Laser (PIRL) scalpel, a device that works by laser ablation or extraction with complete energy confinement on single cell dimensions. PIRL avoids collateral damage and ionizing radiation effects on cells close to the area where the scalpel is at work. The absence of tissue damage — beyond a single targeted cell line — discourages formation of scar tissue in patients. This aids in healing and has provided new insights into scar tissue formation.
PIRL will be going into preclinical trials in 2025.
“This new atomic-level insight into strongly driven phase transitions defined the laser conditions to produce rapid phase changes without unarrested nucleation (bubble) growth and shock wave formation that otherwise leads to massive collateral damage in patient tissues. It enables the long-held promise of the laser to achieve surgery at the fundamental single cell limit, with complete biodiagnostics for surgical guidance.”
Miller presented this side of his work and latest advances at Brock University this March when giving a talk on ultrafast lasers and their applications. “It is hardly minimally invasive if you remove the wrong tissue. Now we have hundreds of molecular markers—like a molecular bar code — to identify tissue. We can use this technology to detect disease at the earliest, single cell level, of detection.”
“PIRL goes beyond scar-free surgery. It looks like we can do site-selective drug delivery anywhere in the body. This may mean treating cancers with 10,000 times less drugs to avoid the horrors of side effects in chemotherapy.” These are just some of the outcomes from the first atomic movies and the promise they offer for understanding structure-function relationships.
Miller says the Plyler Award recognizes a fourteen-year effort by his group, one that began in 1989 with what he calls his Impossible Dream, and encompassed a 1995 move from the University of Rochester, New York to the University of Toronto, which created the chance to build a new lab to focus on bringing the gendanken experiment to reality. “Nobody gave up, even though it took until 2003 to get our first paper out on this topic. My earliest students graduated without seeing us ultimately succeed in this quest, but still made important contributions that paved the way.”
“It’s one thing to have a dream and go for big questions in science, but to have the perseverance and fortitude to cross the finish line is an achievement that I owe to my students.”
In addition to innovations in molecular spectroscopy and dynamics, Miller is passionate about promoting science education through high school outreach. He is the founder of Science Rendezvous, an annual event that draws out tens of thousands of attendees every year across Canada, whose goal is making science accessible and exciting on a grand scale. Or, as he sometimes puts it: “To bring out the inner scientist in all of us.”
Though he and his team are now beyond those years of struggling to make the first atomic movie, Miller’s excitement about his work remains unabated. “We can directly observe the very essence of chemistry and appreciate the beauty it holds. Knowing how something so complicated can reduce to a few reaction modes is the start of understanding complexity.”
“It is chemistry that drives biology. The concepts from this level of microscopy will allow us to proceed with some confidence that we are on the right track to tackling a truly big question: What is Life?"