PhD position.

to work in the field of astrochemistry, and more specifically on the question of Nitrogen chemistry.Scientific context: Nitrogen is, in abundance, the fifth element in our local Universe. This compound is also an essential constituent of molecules related to life. Nitrogen-bearing molecules are observed routinely in the ISM, in diffuse and dense conditions found in translucent clouds or star-forming regions. The reservoir of nitrogen is not well established because neither N nor N2, which are presumably the dominant forms of nitrogen, are directly observable. Hence the determination of the abundance of N is only indirect, and relies on numerical models. Such models have basically two types of ingredients: physical (e.g. density, temperature) and chemical ones (essentially network of the chemical reactions and their kinetic rates). These
two types are then coupled by complex processes. The intimate coupling of the physics and the chemistry makes numerical models unavoidable. In the recent years, evidences have accumulated that show that our understanding of the chemistry of nitrogen is incomplete: models are not able to explain the observational constraints on the abundances of several species. The detection, in both diffuse and dense gas, of simple nitrogen-bearing species with the recently launched Herschel satellite brings further constraints, and opens the opportunity to revisit the chemistry of nitrogen. This is the topic of the PhD thesis here proposed.

Objectives: The successful applicant will work with Pierre Hily-Blant and Alexandre Faure, within a team of
scientists, engineers, post-docs and graduate students to perform

1. Observations: The student will be in charge of a complete observational program using
complementary facilities (ground-based telescopes (IRAM, CSO, APEX) and the space-based
Herschel observatory (HSO)). Our team has already been granted several observation programs
with these telescopes, including a 30~hrs program with Herschel/HIFI. He/she will perform the
observations starting with CSO observations in Hawaii scheduled by fall 2011.

2. Modelling: The student will perform chemical model calculations to be compared to the observations
from which he/she will apply for complementary observational programs. In the process, he/she is
expected to work on the chemical network.

3. Theory: Radiative transfer calculations will complement the modelling effort. The student might be
part of the effort to compute microscopic parameters such as collisional cross-sections. Finally, the
student will build complete models of the sources.
Candidate qualifications: applicants should have a solid background in physics. Knowledge in basics
astrophysics and strong interests in observations and modelling are desired. Knowledge in atomic and
molecular physics is an advantage. Knowledge in chemistry is a plus. A participation in some teaching duties
is expected.
Conditions: the full-time position is for 3 years. The brut salary is 31000 euros/year. The student will spend
part of the time (amount to be agreed with the candidate) in Santiago de Chile, benefiting from the vicinity to
the ESO at the moment when ALMA will start its operations. The rest of the time will be spent at IPAG.

Applicants should send a CV and a brief statement of motivation to or, or by mail to Pierre Hily-Blant

IPAG, Observatoire de Grenoble BP53 F-38041 Grenoble Cedex 9.
Further enquires can be made at the same address.