Ahmed Zewail, Priestley Medalist

Ahmed Zewail

We send our congratulations to Dr. Ahmed H. Zewail, Caltech’s Linus Pauling Professor of Chemical Physics, who was recently named recipient of the 2011 Joseph Priestley Medal, the highest decoration granted by the American Chemical Society.  Dr. Zewail is, of course, no stranger to major honors, having received the 1999 Nobel Prize for Chemistry.

As with the Nobel award, Zewail’s Priestley medal is being granted for his groundbreaking research in femtochemistry.  Zewail was the keynote speaker at our 2001 Pauling Centenary Conference and his address, titled “Timing in the Invisible,” serves as a useful introduction into the fascinating world of femtochemistry – broadly defined as the study of atomic behaviors that occur in very short periods of time.

In his 2001 talk, Zewail described the experiments that his laboratory had, at the point, developed in their quest to measure the activity of very small, very fast systems.  Using homegrown laser technologies, the Zewail group first succeeded in making simple observations of the periodic stretching and compression of bonds between two atoms.  From there, the researchers moved on to more complex investigations, including measurements of the energy needed to break the bonds of a given atomic arrangement.

The speed of the processes that Zewail’s laboratory studies are mind-boggling to the non-scientist.  As Zewail described it, one primary use of femtoscience is the study of “the fundamental vibrational time scale” – the “spring-motion” movement of two bonded atoms – that occur in tiny segments of time ranging from 10^-12 to 10^-14 seconds.

And as it turns out, there are many practical applications that have emerged from femtoscopic research, including, for example, the mechanics of human vision and the properties of photosynthesis in plants.  Femtoscopic experiments also provide a method for researchers to determine the amounts of energy that hold together different types of chemical bonds. In effect, femtoscience allows scientists to, in Zewail’s words, “see bonds and atoms.”

Zewail also took a few moments in his Centenary Conference keynote to reflect upon his relationship with Linus Pauling, whom he knew for the last two decades of Pauling’s life.   In doing so, Zewail provided some context for what has become one of more eye-catching artifacts held in the Pauling Papers.

I also organized the 90th birthday for Linus at Caltech, and I think if Linus did not come back to Caltech to share his great moments, it would have been a mistake in the history of Caltech and science. I even crowned him the Pharaoh of Chemistry, and I believe that he loved this picture….It cost me about $500 to do this, because I had to go to Hollywood and try to fit his face into one of Ramses II.

As one might expect, chemistry’s king of kings also received the ACS’s most prestigious award, accepting it at a ceremony in April 1984.  In his speech that evening, Pauling reflected a great deal upon the life and work of Joseph Priestley (who was something of a kindred spirit), and in one particular passage especially, the reader is able to draw a parallel between the award’s namesake and its 2011 recipient.

One of Priestley’s biographers, Gibbs, has asked ‘How was it that, in this difficult and obscure field [of the existence and nature of different kinds of gases] he was able to make advances that had eluded so many men of science?  He himself put it down to his habit of searching into dark and mysterious corners, and of following a scent wherever it might lead, without any preconceived notions.  Almost alone among scientists then living, he was honest enough to credit part at least of his success to enthusiasm and a sense of adventure.