title: Electric field effects in the excitation of cold Rydberg-atom pairs.
abstract: In this work, we study the role of the ac Stark effects on the excitation of nS1/2 cold Rydberg atoms produced in a rubidium magneto-optical trap. We have observed an atomic population in the nP3/2 state after excitation of nS1/2 for 29<or=n<or=37. Such an observation is normally attributed to binary collisions; however, the interaction between Rb nS1/2 atoms is repulsive. To explain our results, the dipole-dipole interaction and ac Stark shifts from the excitation laser must be considered. We find that the Rydberg-atom-pair state asymptotically correlating to nP3/2+(n-1)P3/2 is excited directly.
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970, São Carlos-SP, Brazil.
authors.forename: V A
authors.initials: VA
authors.lastname: Nascimento
authors.forename: L L
authors.initials: LL
authors.lastname: Caliri
authors.forename: A
authors.initials: A
authors.lastname: Schwettmann
authors.forename: J P
authors.initials: JP
authors.lastname: Shaffer
authors.forename: L G
authors.initials: LG
authors.lastname: Marcassa