Abstract
Abstract
We study both theoretically and experimentally the energy dependence of the low-energy Rb+–Rb total collision rate k
ia in the energy range from 103 to 104 K. We calculate the integral elastic cross-section and the resonant charge-transfer cross-section by the quantum mechanical molecular orbital close-coupling method, and then obtain k
ia for temperatures by averaging the cross-sections over a Maxwell–Boltzmann velocity distribution. The experiments are conducted in an ion–neutral hybrid trap, where the Rb+ ions are created by photo-ionization of the cold atoms in a magneto-optic trap (MOT) and accumulated in the linear Paul ion trap. The total ion–atom collision rate k
ia is measured by monitoring the fluorescence reduction of the steady-state MOT atoms by sequentially introducing photo-ionization and ion–atom collisions. The ion–atom collision energy E
col ≈ T
i is modified by changing T
i due to T
i being more than six orders of magnitude larger than the T
a of cold atoms. The temperature of ions T
i is obtained by comparing the time-of-flight mass spectrometry of Rb+ from experimental results to that obtained by SIMION simulation. The equilibrium steady T
i is modified by changing the initial root-mean-squared position of the ion cloud, and the k
ia are measured with E
col from 8000 to 16 000 K. Both the theoretical and experimental results show that k
ia increases with E
col. More specifically, the measured k
ia increases rapidly with the enlargement of E
col near 10 000 K. The theoretical calculation results show that k
ia increases slowly with E
col. The specific difference may be due to the influence of the ratio of excited states f
e on the trend of k
ia at different E
col.
Funder
National Key Research and Development Program of China
National Natural Science Foundation of China
Key Research Program of the Chinese Academy of Sciences
Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics
Subject
Condensed Matter Physics,Atomic and Molecular Physics, and Optics
Cited by
1 articles.
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