Seeing the atoms dance
As told by Paul Alivisatos

It’s an honor to be recognized alongside two other scientists whose work I admire and cherish, Robert Langer and Chad Mirkin. Insofar as this is a recognition of me as an individual, I begin by thanking my family, my spouse Nicole, without whom this journey would not have been possible, and our daughters, Clara and Stephanie, who long ago transitioned from childhood, blossoming as adults into being our life partners.

And of course, I would be beyond remiss if I did not acknowledge the extraordinary community of doctoral students, postdoctoral scholars, undergraduates, and staff who worked in my research group and who in sum have helped shape our corner in the field of nanoscience. This is surely their prize.

Yet, I am above all an institutionalist. It seems right on this occasion for me – the individual being honored – to pay tribute to the extraordinary institutions and the communities of scholars and scientists that have shaped me along the way to receiving this prize. In my view, they are justly thought of as true co-creators of the discoveries we are honoring.

An inspirational image
It is such a signal honor to be awarded the Kavli Prize in nanoscience. It is a kind of recognition that would be utterly unimaginable to my twenty-year-old self. Yet, that is precisely the age when an image first entered my imagination. It has stayed with me since, forming a kind of background dream that always reminds me of a direction that is worthy. This image came to me in the beautiful Harper Library of the University of Chicago— the institution that taught me how to think. As an undergraduate student there, I was enraptured by the core curriculum, a set of classes from across all disciplines, from humanities, social sciences, biological, physical, and mathematical sciences, as well as the study of a civilization. The aim of these classes to this very day is to help students learn to think about problems from many different perspectives and with a variety of intellectual tools.

I loved my class in beginning chemistry, the study of atoms and molecules fascinated me, and yet my devotion to chemistry was still uncertain. I was looking for something I could draw inspiration from, something that would seem exciting and beautiful. I was so lucky when this came to me, in of all places, a particular laboratory experiment in my third year physical chemistry class.

The lab involved the study of how a metal whisker-shaped wire formed and grew inside a vacuum chamber. The wires formed when a gas of metal atoms was introduced into an environment where there was a cold plate across from a phosphor screen. Metal atoms would condense on the cold plate and, under the influence of the electric field, they formed wires that grew in the direction of the phosphor screen. The electric fields were large enough that electrons could escape from the very sharp tips of the growing wires and then accelerate into the screen, lighting it up. The brightness of the resulting spots could be used to infer how close the wires were to the screen, and hence the length of the wire. It was with a sense of delight that I saw these spots grow in brightness only to extinguish abruptly when the wires reached the screen and shorted out, vaporizing the wires.

"I was looking for something I could draw inspiration from, something that would seem exciting and beautiful."

To my surprise, the real inspiration came not in the lab itself, but later in the library, when I learned that it was possible to go much further, to infer the rate of growth of the wires from their brightness over time, and then to prove that the only way for the growth rate to make sense was if metal vapor atoms could impinge on the wires at any point along their length and then migrate to the end. For me, this idea that it was possible to know how atoms move on the smallest scale, to see them dance as it were, to explain those motions, and to use this to build things, was an inspiration. It is what I have worked on as a nanoscientist ever since. It is the picture in my mind that, through unpredictable twists and turns, led to the discoveries honored with this great prize.

Complementary academic approaches
Today, I can see the younger me in that library and I see something much larger than my moment of inspiration. I see an entire university, the University of Chicago, as a community of scholars who love knowledge so much that they impress its’ inestimable value on young persons; who honor above all those who carefully and over time, layer-by-layer, reveal and understand what lays beneath the everyday, what at first is hidden, but that can become known for all to see and understand. What an honor it is to serve today as president of that university, where I was raised with this way of thinking and being.

So much of my life is entangled forever with my other great university love, the University of California, Berkeley, and the College of Chemistry there, as well as the Lawrence Berkeley National Lab. I spent the great majority of my scientific life at Berkeley, and that is where the discoveries being honored today actually took place. The journey to Berkeley is one that young people undertake with a sense of adventure and hope. That certainly was the case for me personally, as well as for the many scholars who worked with me there over the years. In my experience at Berkeley, knowledge is revered and created in a very different way than at Chicago. It is almost the inverse, or certainly the essential complement. The Berkeley way is to constantly study a subject with a view toward finding where our knowledge is genuinely lacking, to find the way in which our understanding must be upended, to see things in an entirely new light.

A new way of looking at nano crystals
This was how it played out for me. When I began a research group there in 1988 as an Assistant Professor of Physical Chemistry, the study of colloidal nanocrystals was completely unknown in the Chemistry departments of major US universities, and there were maybe four scientists in the world working on this topic. We had the opportunity to study such foundational aspects of tiny nanocrystals as the size dependence of their melting temperature, their structural transformations under high pressure, quantum size effects on their optical properties, and more. Underlying it all were a series of studies on their growth mechanisms. The spirit of adventure of those times was very real as we embarked on honing a new discipline as it was coming into being and which today is represented by many thousands of researchers at universities worldwide.

"The spirit of adventure of those times was very real as we embarked on honing a new discipline."

I will never forget that my chemistry colleagues at Berkeley, following our work closely, went ahead and promoted me to tenure years early, before I even had my first research funding, because they could tell that something really new was afoot – a different way of looking at materials, at making them, at understanding them, this time based on studying the tiniest of crystals, rather than their macroscopic counterparts. It was just in this time that my own lab and a handful of others, including that of this year’s Nobel Laureate in Chemistry, Moungi Bawendi, developed practical synthesis of reliable colloidal nanocrystal quantum dots that were bright, photostable, and had tunable emission energies.

Just a few years later, a new period emerged, and for me that period will forever be linked with the culture and ethos of the Lawrence Berkeley National Lab (LBNL) and with the marvelous way in the US Department of Energy has fostered science in the network of National Labs that it stewards. It was not long after the early colloidal nanocrystal studies that it became clear that this would be an important area of science with many potential applications. This discovery arose from a spirit and practice of open team science, of deliberately engaging science to bring technology benefits to humanity. LBNL fosters an environment where such fields can truly flourish, where it is possible for scientists from many different disciplines to connect with each other and to think together how to bring new discoveries to the next level. In this moment, I was able to explore twin tracks.

One was to see if the new generations of colloidal nanoparticles would have some useful applications. A second was to explore the ways in which the fabrication and study and applications of nanomaterials could be greatly accelerated. The latter effort resulted in our launching the Molecular Foundry, which to this day is a national facility, sponsored by the Department of Energy, and that is a remarkable place of sharing in nanoscience to the benefit of open science.

Quantom dots as biological tags
The second track emerged during the workshops for planning the Foundry, when I met Shimon Weiss, a brilliant physicist who was studying single molecule spectroscopy and its applications in bioimaging. I still recall our sitting together at a workshop and excitedly realizingjust how remarkable colloidal quantum dots could be as biological tags. We were fortunate as well to be joined by a graduate student, Marcel Bruchez, who worked closely with us on realizing this idea for the first time. I am so sad that Marcel, who did so much to develop the earliest coatings and functionalization of colloidal quantum dots, essential for the first demonstration of bioimaging, is not able to be part of these celebrations. He passed away far too early from glioblastoma. His spirit of discovery and his energy will always remain with me.

Our first publication was in 1998, back-to-back in Science with a related paper by Shuming Nie. Even as our first work was early in development, we knew full well that there would be many applications. Indeed, there would be far too many for us to ever imagine them all. It is for this reason that we set about working with others to establish Quantum Dot Corporation, which, within less than two years had brought these biomarkers with a broad range of functionalization to the commercial marketplace, making them readily available to biomedical researchers from around the world.

"To me, those tiny crystals and how they form are beautiful and captivating."

Crucial long-term support
None of this would have been possible without the long-term support of the Office of Science of the US Department of Energy. This organization is one I admire so much. Here is what I experienced: It steadfastly supported the period of foundational science that was required, it cultivated and enabled me as a beginning scientist, and it fostered team science at the National Labs. It made it so that my discoveries could take practical form and be shared widely, and it did all this with a willingness to make big bets and stick by them. I am so grateful.

Remember though, those atoms dancing on the wires? To me it is just as important a part of this story that still to this very day—each and every day—I am able to work with an incredible team of scientists, who together with me are learning how to make even better nanoparticles, even to image them as they grow and form. To me, those tiny crystals and how they form are beautiful and captivating.