72
SOLEIL
HIGHLIGHTS
2013
The gas phase offers a unique solvent-free and substrate-free environment
in which isolated species can be interrogated by photons over a wide spectral
range, spanning from far IR to the X-rays.
Fundamental research, often based upon a rich experiment/theory interplay,
is carried out on isolated species aiming at studying their electronic and molecular
structures, as well as the dynamics of the photon/matter interaction and the
associated many-body couplings. Along this line, Kimberg et al. used high-resolution
Resonant Photoemission coupled to high level ab initio calculations to unravel
with an unprecedented accuracy the molecular potentials of N
2
+
, as well as the rich,
associated fs nuclear wave packet motion, while Kushawaha et al. observed and
modeled double-slit-like interferences in the inner-valence photoionization
of small symmetric hydrocarbons, providing structural information, such as the C-C
distances. Travnikova et al. pointed out a specific ultrafast dissociation mechanism
in core-excited polyatomic species involving multi-mode dynamics on a barrierless
potential energy surface. Electron imaging in coincidence with ions (iPEPICO)
was used by O’Keefe et al. in a synchrotron+laser two-color scheme to observe
an isotope-dependent complex autoionization dynamics in Xe atoms, while Garcia
et al. observed by photoelectron circular dichroism (PECD) on a chiral species
a striking electron/nuclear motion coupling as evidenced by a reversal of the electron
angular asymmetry according to the ion vibrational excitation.
Another part of the activity concerns studies at the interface with other fields
in which gas phase species are encountered (astrophysics & planetology) or are
studied as model systems, i.e. elementary bricks of more complex matter (chemistry,
biology). Along this line Rousselot et al. derived nitrogen isotopic ratio in amine
(NH) functional group-containing molecules, by comparison between emission
lines obtained from the ESO telescope and from laboratory based FT-spectroscopy,
shedding light on the solar system formation. On alanine, the simplest proteic
amino-acids, Tia et al. measured a clear signature of PECD, a chiroptical conformer-
dependent effect, which could be an asymmetric photophysical effect linked
to the origin of biomolecular asymmetry, while Milosavljevic et al. studied the effect
of nano-solvation of a peptide dimer ion stored in an ion trap, and observed
an unexpected stability regarding VUV irradiation attributed to the presence
of water molecules in a bridging position between the two peptides.
These experiments are carried out with a large array of experimental set-ups,
in constant evolution and with several major upgrades. Some of these are described
in the Modeling, Methodology and Instrumentation chapter of this document.
Laurent Nahon
Head of the ”Atomic and Molecular Physics, Dilute Matter, Universe Science”
Scientific Section
ATOMIC AND MOLECULAR PHYSICS,
DILUTE MATTER, UNIVERSE SCIENCE
