Proposed interpretation of microwave ionization of Rydberg alkali-metal atoms

I show that the theory developed for quantum delocalization of an excited hydrogen atom in a two-frequency linearly polarized microwave field can be used with a few adaptions to explain the quantum delocalization of alkali-metal atoms in a linearly polarized monochromatic field in the regime where it deviates from hydrogenic behavior. Comparison with numerical and laboratory experiments is satisfactory: apart from a constant factor, independent from the microwave frequency, the same dependence from the initial quantum number is observed.

Figure 1

Comparison of Eq. (20) (full line) multiplied by a factor 3.7 (see text) with the numerical results from Refs. 2, 3 (squares) showing the threshold microwave field amplitude for ionization (conventionally set at 10% ionization) vs initial quantum number. The vertical dashed lines mark the extremes of region II of Refs. 2, 3.

Figure 2

Comparison of Eq. (21) (full line) multiplied by a factor 3.7 (see text) with the experimental results from Ref. 5 (squares) showing the scaled microwave field amplitude for 10% ionization vs scaled frequency. The vertical dashed lines again mark the extremes of region II of Refs. 2, 3.