title: Optical pumping and vibrational cooling of molecules.
abstract: The methods producing cold molecules from cold atoms tend to leave molecular ensembles with substantial residual internal energy. For instance, cesium molecules initially formed via photoassociation of cold cesium atoms are in several vibrational levels nu of the electronic ground state. We applied a broadband femtosecond laser that redistributes the vibrational population in the ground state via a few electronic excitation/spontaneous emission cycles. The laser pulses are shaped to remove the excitation frequency band of the nu = 0 level, preventing re-excitation from that state. We observed a fast and efficient accumulation ( approximately 70% of the initially detected molecules) in the lowest vibrational level, nu = 0, of the singlet electronic state. The validity of this incoherent depopulation pumping method is very general and opens exciting prospects for laser cooling and manipulation of molecules.
authors.affiliation: Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, Bâtiment 505, 91405 Orsay, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Viteau
authors.forename: Amodsen
authors.initials: A
authors.lastname: Chotia
authors.forename: Maria
authors.initials: M
authors.lastname: Allegrini
authors.forename: Nadia
authors.initials: N
authors.lastname: Bouloufa
authors.forename: Olivier
authors.initials: O
authors.lastname: Dulieu
authors.forename: Daniel
authors.initials: D
authors.lastname: Comparat
authors.forename: Pierre
authors.initials: P
authors.lastname: Pillet