Ultrafast lasers helping to make some of the shortest pulses of light ever seen in the UK will be at the heart of a new system to capture the movements of electrons as they move around the nucleus of atoms.
A £3.5 million research grant from the UK Research Councils’ Basic Technology Programme announced yesterday has been awarded to a team of scientists to develop and build the first attosecond laser system capable of freeze-framing and controlling the motion of electrons.
Researchers hope that the attosecond system will reveal fundamental insights into atomic behaviour and may eventually lead to new applications in molecular and surface sciences, nano-scale and biological structures.
Because of their size, electrons move extremely quickly and their motion is measured in attoseconds. One attosecond is one billion-billionth of a second, and an electron orbits a hydrogen atom in 24 attoseconds, or 24 billion-billionths of a second.
To capture the electron in motion the researchers will build a system to produce pulses of light lasting attoseconds. These pulses will then be strobed on to atoms in order to ‘freeze’ their electrons in motion.
‘If you want to see a bullet ripping through a tomato you need to have a microsecond strobe to freeze the motion of the projectile,’ said Dr John Tisch, Project Manager based at Imperial College London. ‘We want to see electron motion and for that we need attosecond resolution. Without attosecond probes, the electron motion would be just a ‘blur’.’
Electrons are behind all the fundamental processes in chemistry, biology and material sciences as they make all the ‘bonds’ in matter, joining atoms together to form larger systems like molecules.
‘Changes in materials – be they molecules, solids or living tissue – can all be traced back to rearrangement of these bonding electrons,’ said Professor Jon Marangos, Project Co-ordinator based at Imperial. ‘Attosecond pulses will give us the ability, for the first time, to measure and probe these very fast changes and shed new light on the dynamic processes that occur on this unexplored timescale.’
Currently the shortest measured laser pulse is around 4 femtoseconds (4000 attoseconds) and the shortest light pulses measured are around 600 attoseconds.
The planned length of the pulses in the UK attosecond system, generated using a technique known as high harmonic generation, will be about 200 attoseconds.
The research group will comprise of researchers from Imperial, Kings College London, and the universities of Oxford, Reading, Birmingham, Newcastle and the Rutherford Appleton Laboratory, Oxfordshire.
The groups will each build separate components and the final working system will be assembled and operated at Imperial College by 2005.