Two-photon laser optogalvanic spectroscopy of the Rydberg states of mercury by RF discharge

We present new experimental data on the highly excited levels in mercury using the laser optogalvanic detection technique in conjunction with RF discharge. The 6snp P-3(0) (13 less than or equal to n less than or equal to 27), 6snp P-3(2) (13 less than or equal to n less than or equal to 30) and 6snf F-3(2) (10 less than or equal to n less than or equal to 42) Rydberg series have been observed via two-photon excitation from the 6s6p P-3(0) intermediate level, which is collisionally populated in the discharge. The 6snf F-3(2) Rydberg series to such high n-values is reported for the first time. The first ionization potential of mercury is determined from the unperturbed 6snf F-3(2) Rydberg series as 84 184.15 +/- 0.05 cm(-1).