Molecular complexity in space (Objectives)
Over the last decade, the presence of large molecules in
space has been well established through their infrared
emission signatures (eg., the IR emission features) and
their visual absorption bands (eg., the Diffuse Interstellar
Bands). Their charge state is a balance between
photo-ionization and electron recombination. Photons also
play a fundamental role in determining their overall lifetime
through photo-dissociation of the carbon skeleton and the production of
specific fragments. The other
process that is thought to play a key role in the evolution
of large molecules is the interaction with energetic
particles in shocks.
Combining laboratory and theoretical studies into astronomical models of interstellar
sources, the network will explore the evolution and
the physical and chemical characteristics of large molecules in
space. Specifically, the importance of the electron density,
UV photolysis and
shocks for the chemical evolution of large molecules will be
quantified. In addition, this study will be supplemented by
laboratory spectroscopy studies on astronomically relevant
species. The network will then predict the observational
signatures for this chemical evolution. In doing this the network
will chart the path towards the identification of new molecules
in the on-going exploration of chemical complexity in space.
The emphasis in this
effort will be on large PAHs and carbon chains.
We anticipate a major breakthrough for the following
- What are the key (photo)chemical reactions of large
PAHs and carbon chains in the interstellar medium ?
- What is the relation between the chemical
and physical characteristics of large molecules
(size, charge state, excitation) and the
physical conditions of a region ?
- What are the spectroscopic signatures of large
molecules in space ?