Doppler-free spectroscopy of metastable calcium in a discharge heat pipe

We report on Doppler-free frequency modulation spectroscopy and polarization spectroscopy in a discharge heat pipe of yet unexplored transitions connecting the metastable 3P2(4s4p) state of calcium atoms with the multiply excited states 3P2(4p4p) and 3D3(4s3d). Calcium vapor is efficiently produced in a heat pipe operating in a small Pyrex cell filled with 2 torr of neon. A dc discharge running at 500 V efficiently populates the metastable triplet states. Narrow resonances with bandwidths of a few tens of MHz with excellent signal-to-noise ratios are observed, well suited as references for laser frequency stabilization. Examination of the Zeeman shifts lets us determine the Lande g factors of the excited states and compare them with the predictions based on the Russel-Saunders coupling scheme. We describe an economic, simple, and robust experimental setup that should work for other alkaline-earth-metal atoms like Mg and Sr, as well as for other solid elements with insufficient vapor pressures at room temperature