Journal of Physics B Atomic Molecular and Optical Physics
Rydberg levels population via energy pooling collisions in resonantly laser excited dense In vapour
Elena Favilla, S Barsanti, Paola Bicchi
Abstract
The production of Rydberg atoms via collisions in a resonantly laser excited dense In vapour is reported. When a dense In vapour confined in a quartz cell, whose temperature is raised above 820 °C, is excited by 100 kW cm−2 laser pulses at 410.3 nm, resonant with the fundamental transition 5 2P1/2 → 6 2S1/2, the fluorescence spectrum shows radiative emissions from Rydberg states, namely those corresponding to the n 2P → 6 2S1/2 series with 9 ≤ n ≤ 23. Fluorescences corresponding to the 5 2D → 5 2P1/2,3/2 transitions are also observed. Analysis of these signals' intensity as a function of several different experimental parameters, such as the atomic density and the laser power density, indicates that the population in the Rydberg levels is produced mainly by energy pooling collisions (EPC). The EPC cross section for the population of the Rydberg levels is also given. The influence on these effects of the presence of a fine structure in the In ground state (5 2P1/2,3/2) is also discussed, as well as the presence of a buffer gas inside the quartz cell.