An ion–neutral hybrid trap is built to study low-energy ion–atom collisions. The ion–neutral hybrid trap is combined with two spatially concentric traps: a linear Paul trap for the ionic species and a magneto-optical trap (MOT) for the neutral species. The total ion–atom collision rate coefficient between87Rb atoms and optically dark 87Rb+ ions is measured by monitoring the reduction of the steady-state MOT atoms by sequentially introducing various mechanisms, namely photoionization and ion–atom collisions. In contrast to other experiments, a concise experimental procedure is devised to obtain the loss rates of the MOT atoms due to photoionization and ion–atom collisions in one experimental cycle, and then the collision rate of cold 87Rb atoms with 87Rb+ ions is deduced to m 3/s with K measured by the time of flight of the ion signal. The measurements show good agreement with the collision rate derived from the Langevin model.

No abstract

No abstract

The influence of an ionizing laser on the pump-probe spectra of 87 Rb over the transition 5 2 𝑆 1/2 , 𝐹 = 2 → 5 2 𝑃 3/2 , 𝐹 ′ = 3 is experimentally studied in an operating magneto-optical trap. These spectral features, including gain peak, a dispersion-like structure and absorption peak, become weak as the intensity of the ionizing laser increases. Moreover, the profiles of the absorption peak and gain peak vary as the ionizing laser intensity changes. Such results indicate that there is more than one component in the two features and that each component has different dependences on the number of 87 Rb atoms.

The probe transmission spectra around the atomic transition 5 2 𝑆 1/2 , 𝐹 = 2 → 5 2 𝑃 3/2 , 𝐹 ′ = 2 of 87 Rb are measured in a magneto-optical trap by adding a coupling field around the atomic transition 5 2 𝑆 1/2 , 𝐹 = 2 → 5 2 𝑃 3/2 , 𝐹 ′ = 2. The inversionless amplification is observed in the spectrum over the atomic transition 5 2 𝑆 1/2 , 𝐹 = 2 → 5 2 𝑃 3/2 , 𝐹 ′ = 2. The tripod electromagnetically induced transparency is proposed to account for the amplification feature, in which population distributions among these related atomic levels play an important role.