June
6, 2001, marked the inauguration of the ELYSE project, a multidisciplinary
fast kinetics center with a FRF 41 million budget created by the CNRS
and the Université Paris 11 at Orsay, in association with the
Ministry of Research and the Ile-de-France and Essonne regions. ELYSE
represents a national resource for the study of elementary physical,
chemical and biological reactions.
ELYSE's
electron accelerator will deliver 3 to 9 MeV electron pulses of less
than 5 ps. Photoelectrons are generated by a picosecond synchronized
laser system which can generate femtosecond photon pulses independently.
This new electron accelerator has been designed and is now being assembled
by the "Laboratoire de l'Accélérateur Linéaire"
(LAL) at Orsay. It is unique in Europe and the third accelerator of
this type in the world. This ultrafast pump-probe facility at Orsay
can initiate reactions using both ultrashort electron pulses (radiolysis)
or photon pulses (photolysis) to produce different reactive species
for the observation of reaction pathways with a resolution of a few
femtoseconds for photon pulses and a few picoseconds for electron
pulses.
Ultrafast
spectroscopic techniques such as ELYSE's constitute a powerful tool
in basic research and can be applied to many fields, including free
radical generation in liquids ; the kinetics of electron-hole pair
recombination induced in semiconductor micro-crystals ; UV or drug-induced
DNA degradation mechanisms; the physico-chemical processes involved
in inserting different species into cooled helium aggregates ; and
using pulsed radiolysis and photolysis fluorescence spectroscopy to
study the dynamics and reactivity of condensed phases in biological
media.
Studies
recently carried out at Orsay include nanosecond pulsed radiolysis
research on the formation of the latent photographic image ; the optical
limitation properties of suspensions of metal aggregates synthesized
by radiolysis and applied to systems for protecting ocular and optronic
systems under intense laser pulses ; and the radiolysis of solid state
proteins. ELYSE is currently improving its photobiology facilities,
and is making plans to study solid protein radiolysis, which, for
example, is of great interest for optimizing sterilization by irradiation.
