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Summer Science Exhibition 2008

Can we freeze time? Using lasers to film the secret lives of atoms - frame by frame









The Royal Society, London, 6-9 Carlton House Terrace, London, SW1Y 5AG


Galloping horse by Muybridge - unravelling motion too fast to see with the naked eye [Credit University of Pennsylvania Library].

Imperial College London

Researchers at Imperial College have developed a way of observing the inner workings of atoms. So far the molecular movement of hydrogen and methane has been 'filmed' but the system could one day enable complex reactions to be understood and controlled at their most basic.

'To image the movement of something extraordinarily fast like an electron in an atom you need to work with something even faster,' explains John Tisch, a physicist at Imperial. 'Our technique is based on ultra-short bursts of laser-like light, that freeze the movement of electrons, just like a strobe light effect.'

The scale at which the team are working is measured in attoseconds, one billion billionth of a second, with the state of the art being flashes of light at 100 attoseconds. 'It is like slicing the distance from here to Jupiter into hair's widths,' says John.

Lasers were previously limited to pulses of light at the femtosecond scale – a million billionth of a second. An additional step in the process that boosts and concentrates the laser energy was the breakthrough needed to achieve the faster speeds.

'This process generates an x-ray pulse that is faster than the original laser light pulse,' says John. 'Giving us this new attosecond timescale.'

See videos of their exhibit in action on YouTube, and read more at the Imperial College London website.

Can we freeze time? Using lasers to film the secret lives of atoms - frame by frame The Royal Society, London 6-9 Carlton House Terrace London SW1Y 5AG UK