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Dynamics of molecule formation on interstellar ices: thermal or UV-induced?
Applications (deadline October 10 2007) are invited for either a PhD
position or a postdoc position for theoretical research on the
dynamics of chemical reactions on ice surfaces at the Leiden Institute
of Chemistry and Leiden Observatory of Leiden University, The
Netherlands. The research will be carried out in the framework of a
collaboration between the Theoretical Chemistry group
(Prof. G.J. Kroes, Dr. R.A. Olson) and the Astrochemistry group
(Prof. E.F. van Dishoeck), with funding from the Netherlands
Organization for Scientific Research NWO on a TOP-project "The role of
excited electronic and vibrational states in chemical reactions on
surfaces". A description of the research is given below.
Applications for the postdoc position should include a curriculum
vitae, publication list, and a statement of research interests, and
arrange for 2-3 letters of recommendation to be sent to Professor
E.F. van Dishoeck. PhD student applications should send a curriculum
vitae (with a list of grades for university exams), a brief statement
of research experience, and the names of at least two people who can
serve as a reference. Selection of candidates will start on October 10
2007 and will continue until the position is filled. The starting
date for the position is flexible up to early 2008. Please send
applications to:
Prof. dr. E.F. van Dishoeck
Leiden Observatory
P.O. Box 9513
2300 RA Leiden
The Netherlands
FAX: +31-71-5275819
e-mail: [log in to unmask]
See www.theorchem.leidenuniv.nl
and: www.strw.leidenuniv.nl/~ewine
Project description
==============
In dense interstellar clouds where new stars and planets are formed,
small dust particles (consisting of ~0.1 micron silicates) are covered
by ice mantles consisting of H2O, CO, CO2, CH4 and other species, at a
temperature of about 10 K. Recent observations show that larger
molecules such as H2CO, CH3OH, and HCOOH may be present as well. These
molecules can either form by thermal hydrogenation and oxidation
reactions of smaller molecules such as CO, or by photon-induced
processes.
In the PhD or postdoc project, the above mentioned reactions are
studied by performing molecular dynamics simulations to "make"
particles of amorphous ice in the computer. Next, the reaction of CO
with H on the surface of such particles will be modelled using quantum
transition state theory. In addition, classical trajectory
calculations will be performed to obtain mechanistic insights into the
most important pathways, and to visualize these
reactions. Subsequently, the effects of UV photons, which can
dissociate the H2O ice to form energetic OH and H, will be
considered. Reactions of energetic OH with CO is thought to be a
principle route to form CO2. The central goal of the project is to
determine which chemical reactions can occur on interstellar ices, and
to determine the dominant reaction mechanisms: thermal or UV. If time
permits, photodesorption processes of simple ices will be modelled as
well. Complementary laboratory experiments on these reactions are
being carried at the Sackler Laboratory at Leiden Observatory.
Term of appointment: 4 yr PhD or 2.5-3 yr postdoc
Required: Degree in Chemistry, Physics, or Astronomy, with an interest
in molecular dynamics. Experience with numerical methods and computer
programming will be helpful.
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