Physicists make first 'molecular movie' of light

Aug 10, 2006
Physicists make first ‘molecular movie’ of light
Femtosecond x-ray pulses are used to detect the ultra-fast motion of charged atoms in a THz light field. Credit: University of Oxford

Scientists have made the first ‘molecular movie’ of the elementary interaction between light and matter. They measured what happens on a microscopic level when light travels through a medium in a collaborative project involving Oxford University, the Lawrence Berkeley Laboratory in California, and the Massachusetts Institute of Technology.

The lead author of the study published in Nature, Dr Andrea Cavalleri at the Oxford University Department of Physics, said: ‘We’ve all seen how a stick in a pond appears to be at a different angle depending on whether we look at it from outside or inside the water. At a microscopic level, this effect depends on how stiff atomic bonds are, and with how much delay atoms and electrons respond when they are placed in the rapidly wiggling electric field of light.

‘If you want to understand the propagation of light at microscopic level, especially in some the complex materials that are of interest for modern opto-electronic applications, you need to make a ‘molecular movie’ of how the atoms and electrons wiggle in the light field. To do so, you need to find a camera with an extremely quick shutter speed – that of a handful of femtoseconds (which is less than one thousandth of a billionth of a second).

‘This very fast timescale can be reached with modern laser technology – but lasers can’t see where the constituents atoms actually are. If you want to see this ‘shape’ of a molecule you need x-rays, but there are currently no x++-ray beams with short enough pulses to take snapshots of atomic motions.

‘What we have managed to do is combine ultra-fast laser pulses with electron beams in a particle accelerator, deflecting a small slice of the long electron pulse on a separate orbit of the accelerator. Thus, these electrons radiated short enough x-ray pulses to measure elementary atomic motions on the femtosecond timescale. This enabled us to measure the motion of charged atoms on the ultra-fast timescale with an accuracy of less than one thousandth of one billionth of a meter. This means we are capable of resolving in time the displacements of atoms by less than one atomic nucleus.

‘This technology can now be applied to other elementary processes at the microscopic level, and we can measure their displacements with unprecedented speed and resolution.’

Source: University of Oxford

Explore further: And so they beat on, flagella against the cantilever

add to favorites email to friend print save as pdf

Related Stories

The future face of molecular electronics

6 hours ago

The emerging field of molecular electronics could take our definition of portable to the next level, enabling the construction of tiny circuits from molecular components. In these highly efficient devices, ...

For electronics beyond silicon, a new contender emerges

4 hours ago

Silicon has few serious competitors as the material of choice in the electronics industry. Yet transistors, the switchable valves that control the flow of electrons in a circuit, cannot simply keep shrinking ...

Invisibility cloaks closer thanks to 'digital metamaterials'

Sep 15, 2014

The concept of "digital metamaterials" – a simple way of designing metamaterials with bizarre optical properties that could hasten the development of devices such as invisibility cloaks and superlenses – is reported in a paper published today in Nature ...

Recommended for you

And so they beat on, flagella against the cantilever

4 hours ago

A team of researchers at Boston University and Stanford University School of Medicine has developed a new model to study the motion patterns of bacteria in real time and to determine how these motions relate ...

Tandem microwave destroys hazmat, disinfects

8 hours ago

Dangerous materials can be destroyed, bacteria spores can be disinfected, and information can be collected that reveals the country of origin of radiological isotopes - all of this due to a commercial microwave ...

Cornell theorists continue the search for supersymmetry

10 hours ago

(Phys.org) —It was a breakthrough with profound implications for the world as we know it: the Higgs boson, the elementary particle that gives all other particles their mass, discovered at the Large Hadron ...

How did evolution optimize circadian clocks?

Sep 12, 2014

(Phys.org) —From cyanobacteria to humans, many terrestrial species have acquired circadian rhythms that adapt to sunlight in order to increase survival rates. Studies have shown that the circadian clocks ...

User comments : 0