Influence of electric field on Rydberg $nD$-states of cold lithium atoms

The effect of the weak electric field on the coherent two-photon resonance $2S$-$nD$ is considered in the work by means of recording the fluorescence incidence of Li atoms in the magneto-optical trap. In the course of experiments, it was observed that a separate line is transformed into a band due to the Stark effect under the effect of the weak uncompensated electric field. In this case, the width of the band increases with the increase of the value of the principal quantum n number (or the value of the electric field). It is shown that resonant radiation tuned to the left or right edge of the line allows obtaining gas of Rydberg atoms with a constant large dipole moment $ d\sim e a_0 n^2 $ oriented along or against the field, respectively. The radiation tuned to the center of the band will allow obtaining atomic states with a zero dipole moment but with a large contribution of states with a maximum value of the orbital quantum number $l\sim n$.