■VAHIIA projectーGC-MS 分析担当ポスドク(2年)募集のご案内

Starting date 2013/09

You hold a Ph.D. in analytical chemistry. Your area of expertise is
GC-MS analyses. The aim of these researches will concern the analysis
using GC-MS of volatiles coming from the heating of ices previously
formed and irradiated (UV) at low temperatures (20K) and low pressure
(10-8mbar). These experiments simulate the chemical evolution that
could undergo the organic matter from the interstellar medium to its
incorporation into comets or residues.

Expected Gross Salary: 2361 € per month.

Application must include: CV, motivation letter and two recommendation letters.

End submission for applications: April 2013.

Place: Groupe Astrochimie, Equipe Spectrometries et Dynamique
Moleculaire, Physique des Interactions Ioniques et Moleculaires (UMR
CNRS 6633 - Centre de St Jerome, Aix Marseille University), Avenue
Escadrille Normandie-Niemen, case courrier 252, 13397 Marseille Cedex
20, France.

Contacts:
Gregoire Danger gregoire.danger@univ-amu.fr Tel: +33 4.91.28.82.85
Thierry Chiavassa thierry.chiavassa@univ-amu.fr Tel: +33 4.91.28.91.94
Team website: http://sites.univ-provence.fr/piim/spip.php?rubrique93

Project abstract
The challenges of this project consist in simulating through
laboratory experiments, the chemical evolution of interstellar ices
and grains to understand the evolution of the organic matter during
the life cycle of interstellar grains. Currently, our team is
developing two complementary approaches to study this evolution.
First, we are investigating the chemical reactivity that can occur
within analogs of pristine or cometary ices, by working on small size
systems (two or three reactants). Second, we are investigating the
characterization of refractory residues formed during photolysis and
warming of ice analogs without any degradation using an orbitrap
apparatus. In this new project, we propose to develop a new approach,
which consists in implementing an analytical system for the Volatile
Analyses coming from the Heating of Interstellar Ice Analogs, the
VAHIIA project. This new device will help us to get a better
understanding of the chemical reactions that lead to the formation of
refractory residues. It will also give crucial information on species
that would sublimate during the warming of cometary nucleus. This
system will consist in coupling to an ultra-high vacuum cryogenic
system, a gas chromatography including a mass spectrometer in order to
analyze volatile organic compounds sublimating during the heating of
ice analogs. Therefore, the VAHIIA project will be the missing link
between the two existing projects, and the whole will provide a
comprehensive experimental approach aiming to trace the chemical
history of such analogs by studying the reactivity of ice at low
temperature, analyzing the volatile species sublimating during the
warming, and characterizing the non-volatile residues resulting from
the latter.
Scientific and Technical Objectives
Our objective is to understand the constitution and the chemical
reactivity that occurs in interstellar ices during the life cycle of
interstellar grains and that leads to the formation of refractory
residues, similar residues supposedly carried by interstellar and/or
cometary grains. The first step consists in simulating the formation
of interstellar "primitive" ice as they are identified through
astronomical observations. Once formed at low temperature (10 K) and
low pressure (10-9 mbar), these analogs are subjected to various
processes such as irradiation by ultraviolet photons (Lyman α) or
atomic hydrogen bombardments. They may also be subjected to thermal
processes to temperatures up to 800 K. This first step can be
approximated to an activation step of molecules constituting these
primitive ices, which is monitoring by in situ infrared spectroscopy.
Infrared spectroscopy has the advantage of offering a direct
connection with astronomical observations, making it a preferred
method for analyzing the chemical composition of the solids in the
interstellar medium. Once the volatile species are sublimated, the
sample moves towards the formation of refractory residues (300 K in
laboratory conditions). The understanding of the formation of
refractory residues is an important step to establish what type of
organic matter is available in interplanetary objects such as in
comets or asteroids. For this purpose, we have starting collaboration
with R. Thissen and V. Vuitton (IPAG, Grenoble) for very high
resolution mass spectrometry analysis of these samples using
LTQ-Orbitrap. During the warming of simple ice mixture (one to three
reactants), low resolution mass spectroscopy (quadrupole) can be used
for the analyses of sublimating-species in order to confirm infrared
spectroscopy data. However, low resolution mass spectrometry is not
efficient to identify the sublimated Post-doctoral Position in GC-MS
Analysis