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Dear
Colleagues,
Please, can you bring the following PhD Studentship to the attention of prospective
candidates.
PhD thesis, Université du Havre, LOMC-CNRS-UMR-6294
Title:
Collisional
excitation of NH and ND molecules by H2 :
Theory,
comparison with experiments and astrophysical applications
Summary:
The NH and ND molecules play an
important role in nitrogen interstellar chemistry as intermediates in the
formation of ammonia. Both nitrogen hydrides are also used to study the
physical conditions of prestellar cores where stars form. Finally, they allow
studying deuteration processes in these regions and probe the history of
molecular cloud formation.
Modelling of the observations of
both species requires the calculation of collisional rate coefficients of these
molecules by collisions with the dominant species that are e-, H, He
and H2. Without these collisional data, only approximate
interpretation of the observations is possible assuming Local Thermodynamic
Equilibrium. Therefore, we plan to study collisions between NH/ND and the H2
molecule, that is the dominant collisional partner in the cold interstellar
medium.
Calculating the collisional rate coefficients
is done in two steps:
- Calculation of the interaction potential
energy surface using ab initio quantum chemistry methods,
- Study of the dynamic of the nuclei
using close coupling methods.
The potential energy surfaces of
NH-H2 and ND-H2 being already calculated, the PhD work
will focus on the dynamics in order to compute the first collisional rate
coefficients with H2 for both species. Both the fine and the
hyperfine structures of the two molecules will be explicitly considered in the
calculations. Previously, we will update the NH/ND-He collisional data using a
new highly accurate potential energy surface.
The work will be done in close
collaboration with experimental groups to validate the accuracy of the theoretical
results. The work will also be done in close collaboration with astronomers in
order to assess the astrophysical implications of these new data.
The successful candidate will have a
strong background in fundamental physics or astrophysics. He/She must have a
good knowledge of atomic and molecular physics and a good knowledge of
programming tools.
Starting
October 2016 for a period of 3 years.
Salary: 1700 euros / month (before
tax) / health insurance included
Contact:
François LIQUE