Imperial College Laboratory for Ultrafast X-ray Diffraction (LUXD)

Light induced processes are fundamental in Nature. Indeed, the Sun is the earth's energy source and it's light is captured and converted in a multitude of different molecular processes, on intrinsic ultrafast time scale. Whilst the 20th century was the scientific era in which the structure of matter drove much scientific discovery and technology in the 21st century we are now poised to see the emergence of structural dynamics as a driving force in science and technology. The desire to create "molecular movies" of molecular function and light induced processes has driven rapid technological advances in the area of ultrafast crystallography.

A picture says more than a thousand words. Indeed, the most direct observation of a molecular motion is a time resolved measurement in 'real-space' of the atomic coordinates. The spatial resolution is achieved by crystallography with Angstrom wavelength radiation, while the time resolution is achieved with the generation of intense femtosecond pulses for both the excitation and the X-ray probe. Recent developments in laser technology allow the construction of a laboratory based instrument that is capable of femtosecond time resolved X-ray crystallography primarily using the powder diffraction method.

The instrumentation will enable a large range of science applications, including experiments photopharmacology, solar cell research, energy storage, optoelectronics, pyroelectrics, nuclear coherence research, nanophotonics and plasmonics, colloids and biomolecular structure. A compelling example will be the demonstration of a photoisomerisation reaction of a dye-based photoswitching molecule which is used for photopharmacology and energy storage. The ultrafast measurements will determine the excited state reconfiguration and non-adiabatic dynamics of cis/trans photoisomerisation of the organic molecule. The impact is demonstrated by usage of the indigoid moiety in photopharmacology targets such that light regulates the substrate binding in biomolecular target molecules.

Additionally, studies of the structural dynamics following illumination of solar energy materials are vital to understand and optimise functions In particular, with the rapid developments in the solar cell technology, novel materials and continuous improvements in the efficiency will require ultrafast structural measurements of the materials and even working devices.