Résumé

An international colloquium in honour of Sydney Leach, who passed away in December 2019 is planned for an afternoon in September or October 2022, to take place at the Meudon observatory, organized by LERMA and ISMO. The topics of the meeting will include the last developments in Sydney’s broad range of interest : molecular photophysics and chemistry, molecules in space and astrobiology, together with a retrospective

Justification scientifique

Sydney Leach passed away on December 24th 2019, at the age of 95. Born in Britain, he spent his entire career (since 1946) in France at CNRS and was active to the very end at the LERMA department of the Paris Observatory. Sydney was a pillar of modern chemical physics. He had a major influence in creating a new discipline ‘photophysique moléculaire’ and founded a laboratory bearing this name in Orsay (Now Institut des Sciences Moléculaires d’Orsay, ISMO). Sydney was always interested in diverse scientific areas and their interactions. In particular his interest in astrophysics brought him to spend thirty years in the Paris Observatory. His contributions to the study of the electronic spectra of molecules, especially of radicals and molecular ions, are fundamental and sill relevant today. He extended this field to dynamical aspects of larger species and undertook the study of fullerenes, amino acids and nucleic acids, as well as laboratory tests on the role of ions of polycyclic aromatic molecules in the interstellar medium. One of his latest projects on the international space station, EXPOSE, concerned the survival of plant seeds irradiated by UV radiation in space. Sydney was a Fellow of the Royal Society and active member of IAU.
Many of his colleagues, in France and in the world, felt that a meeting would be very appropriate to pay tribute to Sydney. Such a meeting was originally planned to take place in September 2020. Due to the COVID pandemic, the original project could not be achieved.
With the time passed, we revised the format of the meeting to one afternoon in the Meudon Observatory, where Sydney spent his last thirty years. After a biographical introduction, there will be five scientific presentations about the latest developments in Sydney’s very broad range of interests. The afternoon will conclude with a buffet and a session of music and poetry readings, to remind the cultural environment in which Sydney moved and took an active part.

Programme scientifique préliminaire

Scientific topics :

Molecular Photophysics [The genesis of Sydney’s work in Orsay].
Spectroscopy and Dynamics of Large Molecules, Complexes and Clusters.
Synchrotron Radiation [Sydney served on the European committee that planned the SR Source in Grenoble]
Astrochemistry, astrobiology and the origins of life.

Expected speakers :

David Field (Arhus, Danemark)
Matin Schwell (Université Paris-Est, Crêteil)
David Tepfer (INRA, Versailles)
+ two other speakers to be found