Rydberg's sodium atoms as high-sensitive narrowband reconfigurable microwave detector

An interaction of microwave radiation with high-excited (Rydberg) atoms has been suggested to be used for radiation detection and measurement of its frequency. Our objective in the present work was to investigate experimentally and theoretically the spectrum of the microwave transition 37P-37S in sodium Rydberg atoms in a weak static electric field and to perform accurate measurements of the scalar and tensor polarizabilities of the 37P level. Knowledge of polarizabilities is required to find a magnitude of energy level shifts in atom by known static electric fields. The Na S and P states possess large quantum defects (1.347 and 0.854, respectively), so that a quadratic Stark effect in weak fields is characteristic for these levels.