Seeing the Invisible: watching atoms at work with the human eye

Pratibha L. Gai, a India-born physicist, recalls the day she was the first person to see atoms reacting.

When I was a young girl I was curious about how the medicines we take and energy we use and the amazing number of products we use in our everyday life came about.

They come from chemical reactions. They are reactions between different substances. Chemical reactions are the backbone of human healthcare and technology, which are at the heart of modern society.

However chemical reactions take place at the atomic level. Atoms are the basic building blocks of all the matter. However atoms are extremely small: about one tenth of one billionth of a metre (or about 100 trillionth of a metre; or one tenth of a nanometre (where a nanometre is one billionth of a metre)) in size. In other words, they are invisible to the human eye.

In technology, many chemical reactions take place in reaction environments of gas, liquids and temperatures on surface atoms of materials (solids) called catalysts, which help to speed up the reactions. Chemical reactions are living and constantly changing, just like we humans! I realised that to understand living chemical reactions to help develop new medicines, environmentally friendly energy sources and improved industrial products for the benefit of humanity, we needed to directly watch them working at the atomic level.

Around the world old methods to study chemical reactions (often in ‘dead’ environments of vacuum) have not provided reliable information on what happens when living chemical reactions are taking place on catalyst surfaces at the atomic level. So historically text books have a lot of hypotheses. As one can imagine, watching and catching tiny atoms working in extreme conditions of gases and temperatures (up to several hundred degrees centigrade) is a formidable challenge. Conventional wisdom thought that it would be impossible to do. So I decided to do something about it and to help unlock the mysteries of the changing atomic world in chemical reactions.

So, I developed, with my team, a new type of microscope, called the atomic resolution-environmental transmission electron microscope (atomic resolution-ETEM). For the first time in the world this new microscope (atomic resolution-ETEM) technology enables the human eye to watch and analyse chemical reactions on surface atoms of catalysts in reaction environments at the atomic level, in real-time. No more hypothesis, or imagining is required!

The new technology development has thus opened up a whole new field of scientific research across the world for visualising directly dynamic (living) materials working at the atomic level in chemical reactions.

My development of instrumentation and applications did not happen overnight. It required determination, dedication, passion and enthusiasm for research. After graduating with a Ph.D. in physics from the University of Cambridge, I moved to the University of Oxford and established and became leader of the surface reactions group. There I began to explore ways to directly observe living chemical reactions and developed the first prototype microscope instrumental modification at Oxford. I then went to the United States of America for better opportunities to develop the instrumentation a bit further and returned to the University of York, UK, to develop an advanced atomic resolution-ETEM microscope instrumentation.

My scientific illumination came when I realised that it was possible to design and drill holes on the side of an electron microscope in its imaging lens (it is like drilling through its heart!) to enable reaction environments inside the electron microscope and still have it work, and then used it to actually watch for the first time in the world, atoms working in chemical reactions. One day I was alone in my lab testing my instrument. I switched the electron beam on and passed the gas and heated the sample and saw with my own eyes atoms working in live chemical reaction in gases and in temperatures and changing the atomic structure. It was absolutely thrilling. No one had done it before!

The instrumentation technology is quite complex. With this new microscope development we can glimpse into the complex nature of the atomic world of catalytic surfaces and understand the ways that atoms move and reorganise during a live reaction cycle. This understanding is leading to ways of making chemical reactions more efficient and device revolutionary chemical reactions in the production of new medicines, renewable energy sources using plant biomass (including weeds and grass), and other industrial products.

In addition to opening up a new scientific field, other benefits of this research include, the development of tiny antibiotic nanoparticles for surgery and medical implants, to control bacterial infections in healthcare settings and to control infections within the human body.

My research has also contributed to the development of a green dry coating process on the nanometre scale for titania pigments to make them durable for paints and strong polymers, without resorting to environmentally toxic chemicals.

The microscope (atomic resolution-ETEM) development is adopted for commercial production and is being used by numerous researchers worldwide in many areas of science and technology, resulting in further benefits to society. So the applications of the microscope are immense.

In addition to my scientific research, I have helped to create a world leading Nanocentre at the University of York. I am involved in teaching and mentoring students. Our Nanocentre has trained more than 100 science students within a few years, both male and increasingly female, in the advanced nanosciences for the 21st century.

I am passionate about promoting women in science. L’Oréal-UNESCO For Women in Science awards are tremendously important as they help put women scientists’ research on the global stage and this visibility is motivating younger women to take up scientific careers. After all women make up half the population and more women in science means more benefits to the world. That is my vision.

For Women in Science

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