Study of the capture of a Rydberg electron by a molecule (BaF,BaF+)

Equipe MFC : Hans Lignier
Study of the capture of a Rydberg electron by a molecule (BaF,BaF+)

This internship deals with the cooling of BaF molecules in order to perform tests of
fundamental physics.
In our experiment, a cold jet of barium fluoride (BaF) is obtained by a supersonic expansion.
The internal degrees of freedom (rotation and vibration) are cooled by optical techniques we
have recently developed. However, the average velocity of these molecules is about 600 m/s
with a dispersion on the velocity of about 20 m/s (which corresponds to a temperature in the
kelvin range).
Our objective is now to stop the molecules. To do so, we are developing an original strategy:
an electric pulse slows down the temporarily ionized molecules before being neutralized. Last
year, we have demonstrated that our electric decelerator is working well on BaF+ resulting
from the BaF photionization.
From now on, we want to neutralize the molecules thanks to the capture of an electron
provided by a Rydberg atom. The Rydberg source is an oven of caesium atoms duly excited
by three CW laser sources.
The objective of the stage is to achieve and study two types of capture: neutralization of BaF+
to BaF and ionization of BaF to BaF. In particular, we want to understand which Rydberg
state(s) is (are) more suitable for the electron capture, in which state neutralized molecules
will be and, importantly we want to evaluate heating on the molecules.
Theoretical support will be solicited to help us identify the details of the process under study.
The internship can ideally be extended into a thesis.
Hans Lignier - Contacter
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Batiment 505, Rue du Belvédère, 91400 Orsay

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