Profiles in Excellence - Ahmed Zewail

I recently found out that I've been selected to attend the 67th Annual Lindau Nobel Laureate Meeting. Here Nobel prize winners from chemistry come and meet, lecture and guide the next generation of young scientists. It's an honour to be selected, as  only the top 400 young chemists in the world are invited (special hello to any potential employers reading this). The current list of attendees is awe-inspiring, with the likes of Stefan Hell (2014, shared with Eric Betzig and William Moerner) and Ada Yonath (2009, shared with Sir Venkatraman Ramakrishnan and Thomas Steitz) in attendance. A full list can be found here.

One person who unfortunately won't be there is 1999 winner Ahmed Zewail, who passed away in 2016. Prof Zewail was the first Nobel prize winning chemist that I was aware of due to my interest in physical chemistry. He was born in Egypt and attended Alexandria University before completing his PhD at the University of Pennsylvania. An international scientist, he reinforces some ideas from my previous post.

Ahmed Zewail HD2009 Othmer Gold Medal portrait.JPG

His award was "For his studies of the transition states of chemical reactions using femtosecond spectroscopy." Practically this means that his research group was able to view chemical reactions in slow motion, "seeing" individual bonds being broken/formed. As you can imagine this was an incredible step, hence his recognition with arguably the biggest prize of them all (and a good few others including the Grand Collar of the Nile, his native Egypt's highest honour).

For those who wish to get a more detailed idea of the field of femtochemistry, Zewail's publication list is extensive (This is a good one, if quite technical) and he literally wrote the book on the subject. Briefly, consider a chemical reaction:

A + B => C

Perhaps it's very fast (think of chemical explosions) or quite slow (rust). For argument's sake we can imagine it being quite quick. We can see the amount of A and B decreasing and the amount C increasing over the course of some short time. But imagine we could take pictures every 100 milliseconds, then every 10 milliseconds, then every 1 millisecond (one millisecond is 1/1000th of a second or 0.001 s, a blink takes about 300 ms). Each set of photos would reveal a little more detail, think how much we rely on slow motion in rugby for example (England are currently top of the 6 Nations table, woo!). Or to imagine it in a different way, imagine dancing in a room with a strobe light. Each flash shows you in a new position, but without showing how you got there. If you make the strobe flash more quickly the change in position is less dramatic and a little more of your movement is shown. As the strobe flashes quicker and quicker smaller and smaller movements are visible until you can see every step and the light is essentially constant.

What Zewail's group managed to do, using extremely fast laser pulses, was take snapshots (or flash their strobe light) of molecules every femtosecond, or every 0.000000000000001 seconds. I had to triple check that I'd typed the correct number of zeros there, it should be 14 after the decimal point. That's even faster than something travelling at the speed of light can travel 100 m.

What this means is that even the fastest chemical reactions can be examined in extreme detail, according to the 1999 Nobel Prize press release "The contribution for which Zewail is to receive the Nobel Prize means that we have reached the end of the road: no chemical reactions take place faster than this." So not only do we see the reaction as whole, but how chemical transformations occur on an electronic (i.e. individual bond) basis.

I've worked on fast kinetics using a similar principle to Zewail, although on a longer timescale. So his work being recognised in this way was pretty exciting to me. However on  a higher level than my own fanboying, his work is extremely important and is applied to fields from catalysis to the biology/chemistry interface.

If you’re interested in hearing about my work, you can follow me on Twitter @StubbingScience and the work of GlamSci can be found @GlamSci.


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