One-Photon Laser Spectroscopy of Rydberg Series from Metastable Levels in Calcium and Strontium

Rydberg levels of Ca and Sr belonging to the series msns 3S1, msnd 1D2 and 3D1, 2, 3 (m = 4 and 5 for Ca and Sr, respectively) were excited via one-photon transitions from metastable msmp 3P0, 1, 2 states using a frequency doubled pulsed dye laser. The metastable states were populated with a d.c. discharge and excited Rydberg atoms were detected with a space charge limited thermionic diode. More than 150 new energy levels were determined for 3S1 and 3D1, 2, 3 Rydberg series up to n = 45 (Sr) and n = 60 (Ca).