Photodesorption of water ice from dust grains and thermal desorption of
  cometary ices studied by the INSIDE experiment
  A new experimental set-up INterStellar Ice-Dust Experiment (INSIDE), was
designed for studying cosmic grain analogues represented by ice-coated carbon-
and silicate-based dust grains. In the new instrument, we can simulate physical
and chemical conditions prevailing in interstellar and circumstellar
environments. The set-up combines ultrahigh vacuum and low temperature
conditions with infrared spectroscopy and mass spectrometry. Using INSIDE, we
plan to investigate physical and chemical processes, such as adsorption,
desorption, and formation of molecules, on the surface of dust/ice samples.
First experiments on the photodesorption of water ice molecules from the
surface of silicate and carbon grains by UV photons revealed a strong influence
of the surface properties on the desorption yield, in particular in the
monolayer regime. In the second experiment, the thermal desorption of cometary
ice analogues composed of six molecular components was studied for the first
time. Co-desorption of CO2 and CH3OH with O2 indicates that at high O2
concentrations in cometary or interstellar ices "heavy" ice molecules can be
partly trapped in O2 and release to the gas phase much earlier than expected.
This effect could explain astronomical detections of complex organic molecules
in cold dense interstellar clouds.
