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What is ?attosecond science? and what can it tell us about our world? To find out, Dimensions magazine recently spoke with attosecond science pioneer Dr. Paul Corkum, Director of Attosecond Science at NRC and a professor of physics at the University of Ottawa.
On November 30, 2009, NRC and the University of Ottawa unveiled a new state-of-the-art laboratory at an NRC building in Ottawa. The new lab houses Canada's fastest X‑ray laser flash ' a flash so short that it can freeze the motion of an electron orbiting an atom. Called the Joint Attosecond Science Laboratory (JASLab), this facility will allow scientists to make ?movies? of molecules during chemical reactions and study individual electrons. Such research may eventually lead to scientific breakthroughs in health care, diagnostic medicine, quantum computing, nanotechnology, environmental science and energy.
Question: What is an attosecond?
Answer: It is a fraction of a second ? a very small fraction ? a millionth of a millionth of a millionth of a second. Here is another way to understand it: an attosecond is to a second as the second is to the age of the universe: 13 billion years. A third way is, if you, like Superman, could travel at the speed of light around the Earth, you would circumnavigate the world about 40 times in a second. But in one attosecond, you could only circumnavigate a single atom ' and just once.
Did you know?
- An attosecond is 1/1,000,000,000,
000,000,000 seconds. There are 1018 attoseconds in 1 second. There are 1018 seconds in the age of the universe.
- It takes 160 attoseconds for an electron to orbit a hydrogen atom.
Q: What is attosecond science?
A: Attosecond science involves studying things that happen on the scale of atoms and molecules. It's the science of electrons in atoms, molecules and solids.
Q: Why do we need attosecond science?
A: First, we're made of atoms and molecules, and molecules are held together by electrons. If we want to understand how molecules are bonded, how the bonds change and maybe see those bonds, then we need a technology that allows us to image these things on their time and space scale.
Taking a historical perspective, for centuries we've been learning how to measure things faster and faster. A few hundred years ago, we were trying to make better clocks to help us navigate around the world. One hundred years ago, we were developing the first photographs of horses running. Now we can make movies of molecules and things like that.
Q: What do we hope to find out?
A: It's a bit early to know for sure. Not only have we gone faster than before, but we've developed a completely new technology for doing so. But new technologies take a while to see what they imply. Already, we have learned something that seemed impossible only a few years ago. We can take pictures with Angstrom scale resolution, seeing electrons and atoms of molecules. Of course, we now want to take movies, but what should we make movies of? In the field of electronics, there's a push toward smaller and smaller and maybe trying to make electronic components out of molecules. So, we might be able to use attosecond science to watch the current flow in a molecule. Or it may allow us to look at the dynamics of molecules by taking three-dimensional images. One dream of ours is to develop a means of making a 3D map of molecules inside cells.
Q: Why was the Joint Attosecond Science Lab established?
A: Attosecond science has advanced to the point where it needs an academic home and a government home. Under the JASLab partnership, the University of Ottawa will provide young researchers and an academic environment for post-graduate students, while NRC will provide its expertise in attosecond science and ability to manage large research facilities. The JASLab will position Ottawa as the attosecond science capital of the world.
Q: Can you describe the JASLab facility?
A: The $2-million laboratory was specially designed to house a state-of-the-art laser system. The equipment is so sensitive that the laser is placed on top of 60 cm thick honeycomb tables that are floating on a cushion of air. The concrete floor slab has been separated from the rest of the building to remove the vibrations of people walking nearby. Special air handling units maintain the temperature, humidity and pressure in the laser room during all of Ottawa's seasons.
The JASLab houses Canada's fastest camera flash ' a flash so short that it can freeze the motion of an electron orbiting an atom.
Q: Can you describe the laser system?
A: It all starts with a laser that produces 80 million pulses of light every second. It uses the same technology that is now used in the latest and most accurate atomic time clocks around the world. Each laser pulse is so precisely controlled that it is accurate to one part in a trillion. One of these pulses is then amplified ' like you amplify sound in an audio amplifier. But when the light emerges from our laser amplifier, it contains much more power than even the largest CANDU reactor. (Fortunately, we won't notice it on our JASLab hydro bill, because the power meter only turns on for a few thousand attoseconds.) We need light this intense to pull electrons off all of the atoms and molecules that it encounters, starting the attosecond pulse production process.
Q: How does the laser system take pictures of atoms?
A: As you may know, light is a wave ' a wave of force on an electron. So, if intense light irradiates an atom or molecule, then the electron can be pulled from the molecule. The light wave makes the electron move away, but then the wave reverses and the electron is driven back, moving much like a cork on a water wave. An image is imprinted on the electron if it collides with the atom or molecule from which it left. We read the image in the attosecond pulse that is generated during the collision.
Q: What does this lab mean to attosecond science? Is it unique in the world?
A: As you can imagine, many laboratories in the world are getting in on the action, so we are no longer completely unique. Our facility will be the only lab producing isolated attosecond pulses in Canada. Hopefully we can change that quickly, moving the technology throughout the country. To my knowledge, there is one laboratory in the U.S. and two in Europe that can also produce isolated pulses.
But we are unique in a different way. Canada has many excellent researchers working in this general area of science ' especially along what I like to call Canada's ?Multiphoton Corridor? stretching from Ottawa to Québec City. This creative concentration, especially in Ottawa, makes us unique in our clear understanding of the subject and its promise.