Author(s)

Marwan Rasamny, Alan Martinez, Lianxin Xin, Jun Ren, Essaid Zerrad

Division of Physics, Engineering, Mathematics, and Computer Science, Delaware State University, Dover, DE, USA.

A cold Rydberg gas, with its atoms prepared initially all in the excited state |n₀> , with n₀ »1, contains an excessive amount of energy, and presumably is to relax by the Penning-type molecular auto-ionization (MAI), in which a portion of excess energy of one atom is given to another near-by atom and ionizing it. Its complementary process, the resonant energy transfer (RET), is discussed, in which the excess energy of one atom is used on another to form a hyper-excited atomic state |n_a> with n_a»n₀. This process is always present, provided certain resonance energy conditions are satisfied. In this report, the n₀ and density dependences of the RET rates are studied in detail, employing a simple model: 1) at low densities, the RET is mediated by the dipole-dipole coupling V_dd and its rates are generally much smaller than that of MAI, especially for small n₀. But 2) as the density increases, our model shows that the rates become of comparable magnitude or even larger than the MAI rates. The V_dd is no longer adequate. We, then construct a semi-empirical potential to describe the RET process. 3) At high densities, we show that the atomic orbital of |n_a> overlaps with that of neighboring atoms, and the electron-electron potential becomes prominent, resulting in much higher rates.

Resonant Energy Transfer (RET), Molecular Auto-Ionization (MAI), Cold Rydberg Gas

Rasamny, M. , Martinez, A. , Xin, L. , Ren, J. and Zerrad, E. (2021) Resonant Energy Transfer, with Creation of Hyper-Excited Atoms, and Molecular Auto-Ionization in a Cold Rydberg Gas. Journal of Modern Physics, 12, 1210-1218. doi: 10.4236/jmp.2021.129074.