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Scientific opportunities in molecular sciences offered by coupling VUV synchrotron radiation with a double imaging electron/ion coincidence spectrometer

Date:
Location:
CP 114
Speaker(s) / Presenter(s):
Dr. Laurent Nahon

Abstract: Within a bottom/up approach of molecular complexity, the study of substrate- and solvent-free isolated species is crucial, as they can be considered as unperturbed elementary bricks of matter for which the interplay with state-of-the-art calculations can be pushed as far as possible. 

In this context, probing isolated gas phase matter with VUV (5-40 eV, ie 250-30 nm) allows by photoionization to probe electronic and molecular structures via Photoelectron Spectroscopy (PES), a universal highly sensitive technique. The additional coupling of ion detection in coincidence with the departing photoelectrons (PEPICO) opens large alleys of research in physical chemistry especially when one deals with complex media (molecular beams, chemical/combustion reactors) for which mass-selection of a given species is mandatory. Reciprocally, pure mass-spectrometric analysis capabilities of chemical reactions can be greatly enhanced by the addition of the electronic fingerprint (via PES) allowing the identification of isomers and sometimes conformers of cations with a given m/z.

After a broad introduction to the VUV Beamline DESIRS @ Synchrotron SOLEIL (see ) and its scientific case, the capabilities of our double imaging PEPICO spectrometer coupled to a versatile molecular beam chamber will be illustrated by several examples, relevant to basic physical chemistry as well to interfaces with biology, planetary science and astrochemistry, and dealing with cold molecules, radicals and reaction intermediates, weakly bonded-clusters up to aerosols. Some emphasis will be also given to chiral species probed by a specific chiroptical process based upon photoionization. 

Bio: After a PhD in molecular physics obtained at Universit茅 Paris-Saclay (1991) and a post-doctoral stay at the Department 糖心vlog官方入口 of UC Berkeley (1992-1993), I joined the French synchrotron centers LURE and now SOLEIL. At the head of two VUV beamlines (especially DESIRS @ Synchrotron SOLEIL), for more than 25 years, I have been working on VUV photodynamics (absorption, photoionization, fragmentation) on a wide range of samples, mainly isolated species such as cold molecules, radicals, clusters, trapped ionic biopolymers and nanoparticles. My work is centered on fundamental molecular physics and gas phase physical chemistry, with strong interfaces with chemistry, life sciences, planetary sciences and astrophysics. 

Among this large field, part of my activity is focused onto the interaction of Circularly Polarized Light and chiral species and in particular onto Photoelectron Circular Dichroism (PECD) at the field crossing between molecular photoionization and chirality.