Sterrewachters,
Below please find advertisements for a PhD position on "Models of
Circumstellar Disks" and a PhD and Postdoc position in "Astrochemistry /
Theoretical Chemistry". Can you please distribute them to interested
candidates?
Thanks for your help,
Ewine van Dishoeck
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PhD Position
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Models of Circumstellar Disks around Young Stars
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Prof. E.F. van Dishoeck
Leiden Observatory, University of Leiden, The Netherlands
Deadline: June 30, 2001
A 4-year PhD (AIO) position is available starting this fall within the
Molecular Astrophysics group of Prof. E.F. van Dishoeck at Leiden Observatory.
The aim of the project is to develop radiative transfer and chemical models of
circumstellar disks around pre-main sequence stars for comparison with
existing and future submillimeter and infrared observations. Particular
emphasis will be placed on the effects of UV- and X-ray irradiation of disks,
the heating and cooling balance of the gas and dust, the influence of dust
growth and dust settling, and the excitation of molecules, in particular H2.
Molecular line and dust continuum spectra will be calculated for comparison
with data to be obtained within the context of an approved SIRTF legacy
program. See http://www.strw.leidenuniv.nl/~ewine/ for further information
about Leiden Observatory and the research.
Applications should include a curriculum vitae (with a list of grades for
exams), a brief statement of research experience, and the names of two people
who can serve as a reference. De deadline for the application is JUNE 30, 2001.
The position is open to students of all nationalities with the equivalent of a
"doctoraal" (Masters) degree. The starting date for the position is
flexible. Please send applications to:
Prof. dr. E.F. van Dishoeck
Leiden Observatory
P.O. Box 9513
2300 RA Leiden
The Netherlands
Tel: +31-71-5275814
FAX: +31-71-5275819
e-mail: ewine@strw.leidenuniv.nl
The position is funded by a Spinoza award from the Netherlands Organization
for Scientific Research (NWO).
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POSTDOC AND PHD POSITION IN ASTROCHEMISTRY
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Applications (deadline 30 June 2001) are invited for one PhD position and
three post-doc positions, available starting anytime between July-December
2001, for theoretical research on the dynamics of chemical reactions, 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 (Dr. G.J. Kroes and Dr.
M.C. van Hemert) and the Astrochemistry group (Prof. E.F. van Dishoeck), with
funding from the Netherlands Organization for Scientific Research, NWO. Two
projects involve gas phase reactions, and two projects involve
molecule-surface reactions taking place on ice surfaces. All 4 projects are
listed at http://rulgla.leidenuniv.nl/main_page.html. The two projects
related to astrochemistry are described in more detail below.
Applications should be sent by the June 30 deadline to:
Dr. G.J. Kroes, LIC, Gorlaeus Laboratories, P.O. Box 9502, 2300 RA
Leiden, The Netherlands.
FAX: +31-71-5274488, e-mail: g.j.kroes@chem.leidenuniv.nl.
Candidates for the PhD position are requested to submit a CV, list of
grades, and arrange for two letters of reference. Candidates for the
postdoc positions are requested to send a CV, publication list, and
arrange for three letters of reference.
More information can be found through
http://rulgla.leidenuniv.nl/main_page.html
and http://www.strw.leidenuniv.nl/~ewine.
POSTDOC PROJECT. REACTIONS ON INTERSTELLAR ICE SURFACES
In dense interstellar clouds, 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 ~10 K. Recent observations with the
Infrared Space Observatory (ISO) show that larger molecules such as H2CO,
CH3OH, and HCOOH may be present as well. The current assumption is that these
larger molecules form by hydrogenation and oxidation reactions of smaller
molecules such as CO, which take place at the ice surface or in the ice
mantle. Laboratory experiments on these reactions are being started at the
Sackler Laboratory at Leiden Observatory.
In the project, the above mentioned reactions are studied by first
performing molecular dynamics simulations to "make" particles of
amorphous ice in the computer. Next, the reaction of, e.g., 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. The
central goal is to determine which chemical reactions can occur on
interstellar ices, and to determine the dominant reaction mechanisms.
Term of appointment: The initial appointment is for one year, with
funding available for extension up to 3 years in total.
Required: a PhD in Chemistry, Physics, or Astronomy, with an interest
in molecular quantum mechanics. Experience with numerical methods and
computer programming will be helpful, but is not strictly necessary.
For further information, please contact:
Dr. G.J. Kroes, email g.j.kroes@chem.leidenuniv.nl, or
Prof. E.F. van Dishoeck, email ewine@strw.leidenuniv.nl.
PhD PROJECT: RADIATIVE ASSOCIATION (PhD student, 4 years)
In radiative association, two atoms or molecules combine to form a
single new molecule by releasing their excess energy through photons.
Radiative association is an essential process for the formation of
molecules at low pressures, such as found in interstellar clouds. An
important example within astrochemistry is the radiative association
of a positively charged carbon ion with molecular hydrogen. This
reaction is assumed to drive the entire carbon chemistry in
interstellar space. For the modelling of this chemistry, accurate
rate coefficients are required.
The time-dependent wave packet method will be used to study the
dynamics and determine rate coefficients for the above-mentioned
reaction. The necessary potential energy surfaces will be computed
using high level ab initio methods, as part of the project. The
central goal of the project is to determine the reaction mechanism,
i.e., the relative importance of purely electronic and vibronic
radiative transitions for the stabilization of the product molecule.
Other goals are to determine the lifetime of the collision complex,
the radiative lifetime of the complex, and the dependence of these
parameters on initial conditions.
Requirements: a Masters (or equivalent) degree in chemistry, physics,
astronomy, or numerical mathematics, with an interest in molecular
quantum mechanics. Experience with numerical methods and computer
programming will be helpful, but is not strictly necessary. For
further information, please contact:
Dr. M.C. van Hemert, email marc@rulgle.leidenuniv.nl, or
Dr. G.J. Kroes, email g.j.kroes@chem.leidenuniv.nl, or
Prof. E.F. van Dishoeck, email ewine@strw.leidenuniv.nl.
