Dear all
we would like to introduce the newly created
International Astrophysics Network.
http://po.iams.sinica.edu.tw/~kaiser/network.htm
The prime directives of this network are:
a.to combine the scientific potentials of highly motivated, flexible,
and open minded research groups,
b.to establish goals/research lines investigating and unraveling the
role of neutral - neutral reactions in the gas phase of the
interstellar medium/planetary atmospheres and extraterrestrial ices.
c.exchange ideas what experiments/calculations are necessary and of
paramount importance to the chemical processing of the ISM and
planetary atmospheres,
d.perform experiments combined with theoretical treatment of these
processes in extraterrestrial environments to setup a systematic
database on reaction products and involved intermediates,
e.implement these data into chemical models of various interstellar
environments and planetary atmospheres,
f.guide the search of hitherto unobserved molecules in the ISM and our
solar system.
g.set up a data base to guide future space missions such as cometary
matter return probes, Pluto express, Cassini/Huygens in an
identification of hitherto unobserved molecules,
h.categorize hitherto observed interstellar/cometary molecules
according to their formation route (solid state versus gas phase;
ion-molecule reactions versus neutral - neutral reactions;
distinct classes of neutral neutral reactions
involving atoms, clusters, radicals),
i.encourage exchange of scientists between involved groups.
j.hold periodically informal workshops to advance the
science/strategies in this field.
k.bring this research field into popular science and educational
programs of schools.
The network consists of 6 sections:
Section 1 (laboratory experiments)
Our group (group 1) performs neutral - neutral reactions relevant to
the chemical processing of the interstellar medium and planetary
atmospheres. These experiments provide data on the chemical reaction dynamics,
energy dependent triply differential cross sections, involved intermediates,
and reaction products.
In addition, our solid state machine is involved in neutral atom
and low energy (< 5 keV) ion bombardments of extraterrestrial ice analogues to
investigate the formation of molecules in extraterrestrial ices and on icy
surfaces on interstellar grains. C.S. Lee's group at National Central
University, Taiwan (group 2) performs ion bombardments of icy systems at
higher energies between 5 and 20 keV. The third group ( L. d'Hendecourt et al.)
is involved in ultraviolet photon irradiation of extraterrestrial ice analogues.
These three groups will setup a systematic data base on the reaction
products and involved intermediates and thus provide all the experimental data.
Section 2 (electronic structure calculations)
Electronic structure calculations investigate theoretically gas phase
and solid state neutral - neutral reactions. These calculations will give
information on the involved potential energy surfaces, reaction products,
involved intermediates, and rotational constants together with vibrational
frequencies of reaction products. These calculations are of fundamental
importance in multi-atom systems as studies in groups 1 - 3 . Currently, the
following groups are involved in this section: Y. Osamura (reactions of CN
radicals with unsaturated hydrocarbons); M. Head-Gordon et al. (reactions of
C atoms with small molecules of £ 4 atoms), A. Mebel et al. (reactions of
C atoms with intermediate sized molecules of 5 - 10 atoms), H.F. Schaefer/
P.v.R. Schleyer et al. (reactions of C atoms with large molecules > 10 atoms;
reactions of C2D/C2H radicals; reactions of C2/C3 clusters with small molecules
< 4 atoms; reactions of C6H5 radicals with unsaturated hydrocarbons).
section 3 (RRKM studies)
The results of sections 1 and 2 will be complemented and extended by
(variational) RRKM calculations. This approach will give unprecedented
information on absolute rate constants, theoretical reaction products and
branching ratios if more than one product is formed. These investigations are
performed by J. Peeters et al (Leuven, Belgium) et al (C/C6H6 system, CN/C2D
reactions with unsaturated hydrocarbons, C6H5 reactions, B reactions).
Section 4 (modeling)
Results of sections 1 - 3 (absolute rate constants, reaction
products, branching ratios) will be implemented by T. Millar (UMIST, UK) into
models of molecular clouds, hot cores, and outflows of AGB stars. These models
can predict theformation and abundance of observed/hitherto unobserved molecules
in these environments.
Section 5 (observation)
Based on sections 1-4, astronomers will search for hitherto
unobserved, but postulated reaction products of neutral - neutral reactions in
extraterrestrial environments. The key players in these observations are
B. Turner (NRAO, USA), Dr. Y.N. Chih (IAA, Taiwan), T. Lee (IAA, Taiwan),
C. Lemme (NCU, Taiwan), Y.J. Kuan (NCNU, Taiwan), and Y. Yung (Caltech, USA).
Section 6 (laboratory microwave spectra)
Based on sections 1-3, McCarthy et al will record microwave spectra
of hitherto unobserved astronomical molecules in the laboratory. These data
will provide the rest frequencies necessary for the astronomical search.
http://po.iams.sinica.edu.tw/~kaiser/network.htm
Anyone interested is welcome.
Denis, Ralf, Oskar et al.
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Dr. Denis ROLLAND
IAMS-Academia Sinica
1 Roosevelt Road, sec.4, Taipei 106
R.O.C. Taiwan
tel: (886) 2- 2364 5370
fax: (886) 2- 2362 0200
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