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High Intensity Laser Pulses - A New Frontier in Molecular Science

Embargoed to time of delivery
09.30am London time (BST)
Wednesday 5 September 2001

The behaviour of molecules: their motions, reactions and interactions underlie much of science at the microscopic or quantum level. If we can precisely manipulate molecular processes, this could have a major impact on the chemical and life sciences.

On Wednesday 5 September 2001, Dr Jon Marangos, Quantum Optics and Laser Science Group, Blackett Laboratory, Imperial College, London, will talk about new techniques used to control and study molecular processes using lasers.

Dr Marangos will explain recent advances in laser technology that have created lasers with ultra-short pulses - shots of energy - which last less than one hundred thousandth of a billionth of a second or 0.00000000000001 seconds (10-14s).

The electric field in these pulses is strong enough to alter the molecular structure of matter. The atoms within molecules are effectively stationary over the duration of these very short pulses. This allows the motion of these atoms to be time-captured which is, fully sampled and studied in real time.

These advances in laser technology might enable the synthesis of new biochemicals or provide a fuller understanding of quantum processes.

Dr Marangos says: "In this talk I will give the audience a basic understanding of these new developments. I will explain: the essential features of the lasers; the basic physics behind the interaction of simple molecules with a strong laser field; the use of shaped laser pulses and feedback - illustrated by recent work from several laboratories.

"I will then explain the mechanisms of laser alignment and its use in controlling chemical properties and light emission from molecules. Finally, I will discuss the way that a laser field modifies the reaction pathways of a molecule.

"For me," says Dr Marangos, "our motivation comes from basic physics - to gain a deeper understanding of what is going on in molecular systems, and to determine to what extent you can control the quantum system. The question we ask ourselves is can you control a quantum mechanical system using this very fine tool, a short laser pulse?"

For further information please contact:

Tom Miller
Imperial College Press Office
Mobile: +44 7803 886248

Notes to editors

Dr Marangoss work is based upon the use of a short pulse lasers that have pulse durations of 50 femtoseconds (fs=10-15s) and peak power of more than 1012 Wcm-2. Currently his group is trying to generate shorter pulse durations (less than 10fs) by using a variant of the optical parametric technique. These pulses of varying duration and wavelength will allow the investigation of a wide range of processes in molecules.

These lasers have been used for several investigations of molecules and clusters of molecules. More recently the team has turned its attention to the study of molecules in intense fields where electrons in molecules are forced to move. This movement forces an alignment of the molecules in the electronic field of the laser. This is how the manipulation of molecules might take place.

By studying the radiation generated by lasers, more information is gained about the role of molecular structure on electron dynamics. Dr Marangoss team have carried out the first measurements of radiation harmonic emission on laser-aligned samples of molecules. These reveal enhanced harmonic emission in aligned samples.

For more details, please see the Imperial College laser consortium website:

Or email Dr Marangos at:
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Imperial College of Science, Technology and Medicine is the largest applied science, technology and medicine university institutionin the UK. It is consistently rated in the top three UK university institutions for research quality, with one of the largest annual turnovers (UKP339 million in 1999-2000) and research incomes (UKP176 million in 1999-2000).