Laser-microwave spectroscopy of Au I atoms in F rydberg state

For the first time the energy level positions of Au I atoms have been measured with high accuracy by means of laser-microwave spectroscopy in the 176-211 GHz frequency range. The new measurements cover the range of principal quantum number n=31-34 for Rydberg series F_5/2,7/2. Using our measured frequencies the quantum defect constants for this series are obtained. The description of our spectrometer, measurement technique and results are presented.