In:
Journal of Physics B: Atomic, Molecular and Optical Physics, IOP Publishing, Vol. 53, No. 13 ( 2020-07-14), p. 135201-
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 10 3 to 10 4 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 .
Type of Medium:
Online Resource
ISSN:
0953-4075
,
1361-6455
DOI:
10.1088/1361-6455/ab8b45
Language:
Unknown
Publisher:
IOP Publishing
Publication Date:
2020
detail.hit.zdb_id:
3111439-8
detail.hit.zdb_id:
209218-9
detail.hit.zdb_id:
1363381-8
Bookmarklink