François Dulieu

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Context. The synthesis of water is one necessary step in the origin and development of life. It is believed that pristine water is formed and grows on the surface of icy dust grains in dark interstel-lar clouds. Until now, there has been no experimental evidence whether this scenario is feasible or not on an astrophysically relevant template and by hydrogen(More)
Dust grains in the interstellar medium are known to serve as the first chemical laboratory where the rich inventory of interstellar molecules are synthesized. Here we present a study of the formation of hydroxylamine--NH(2)OH--via the non-energetic route NO + H (D) on crystalline H(2)O and amorphous silicate under conditions relevant to interstellar dense(More)
In the environments where stars and planets form, about one percent of the mass is in the form of micro-meter sized particles known as dust. However small and insignificant these dust grains may seem, they are responsible for the production of the simplest (H(2)) to the most complex (amino-acids) molecules observed in our Universe. Dust particles are(More)
The gas-surface interaction of molecular hydrogen D2 with a thin film of porous amorphous solid water (ASW) grown at 10 K by slow vapor deposition has been studied by temperature-programmed-desorption (TPD) experiments. Molecular hydrogen diffuses rapidly into the porous network of the ice. The D2 desorption occurring between 10 and 30 K is considered here(More)
Molecular hydrogen interaction on water ice surfaces is a major process taking place in interstellar dense clouds. By coupling laser detection and classical thermal desorption spectroscopy, it is possible to study the effect of rotation of D(2) on adsorption on amorphous solid water ice surfaces. The desorption profiles of ortho- and para-D(2) are(More)
Molecular and atomic interactions of hydrogen on dust grains covered with ice at low temperatures are key mechanisms for star formation and chemistry in dark interstellar clouds. We have experimentally studied the interaction of atomic and molecular deuterium on nonporous amorphous water ice surfaces between 8 and 30 K, in conditions compatible with an(More)
The formation of the first monolayer of water molecules on bare dust grains is of primary importance to understand the growth of the icy mantles that cover dust in the interstellar medium. In this work, we explore experimentally the formation of water molecules from O(2) + D reaction on bare silicate surfaces that simulates the grains present in the diffuse(More)
The desorption kinetics of D(2) from amorphous solid water (ASW) films have been studied by the temperature-programmed desorption (TPD) technique in the 10-30 K temperature range. Compact (and nonporous) films were grown at 120 K over a copper substrate. Ultra-thin porous films were additionally grown at 10 K over the compact base. The TPD spectra from(More)
The morphology of water ice in the interstellar medium is still an open question. Although accretion of gaseous water could not be the only possible origin of the observed icy mantles covering dust grains in cold molecular clouds, it is well known that water accreted from the gas phase on surfaces kept at 10 K forms ice films that exhibit a very high(More)
Nuclear spin conversion (NSC) of ortho- to para-H(2) and para- to ortho-D(2) has been investigated on an amorphous solid water (ASW) surface at 10 K, in the presence of co-adsorbed O(2). The dynamics of the nuclear spin conversion could be revealed by combination of resonance enhanced multiphoton ionization spectroscopy (REMPI) with temperature programmed(More)