Toward a Rydberg constant measurement on circular atoms

A high-resolution spectroscopy experiment on the microwave transitions connecting circular states of lithium atoms was performed. A measurement of the Rydberg constant, directly in frequency units, with an uncertainty of less than 10/sup -10/ is reported. This experiment involves a continuous excitation of circular Rydberg atoms and requires typically a 1 ms interaction time with a 300-500 GHz microwave field. To obtain such an interaction time, laser deceleration of a thermal atomic beam and an extended microwave cavity is used.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>