# Laboratoire Collisions Agrégats Réactivité - UMR5589

Université Paul Sabatier - Bat. 3R1b4 - 118 route de Narbonne 31062 Toulouse Cedex 09, France

## First measurements of the index of refraction of gases for lithium atomic waves

We report the first measurements of the index of refraction of
gases for lithium waves. Using an atom interferometer, we have
measured the real and imaginary parts of the index of refraction
n for argon, krypton and xenon, as a function of the gas density
for several velocities of the lithium beam. The linear dependence
of (n-1) with the gas density is well verified. The total
collision cross-section deduced from the imaginary part of (n-1)
is in very good agreement with traditional measurements of this
quantity. Finally, the real and imaginary parts of (n-1) and
their ratio \rho exhibit glory oscillations, in good agreement
with calculations.

Voir en ligne : Phys. Rev. Lett. 98, 240405 (2007)