Saturation of the $Ca$ intercombination line and its application to spectroscopy and frequency standards

Experiments were carried out using a $Ca$ atomic beam and a tunable dye laser. Lamb dips were obtained in the fluorescence line of various $Ca$ isotopes. It is shown that the narrow signals associated with saturation of the $4s^2{}^1S_0-4s4p{}^3P_1$, intercombination transition are potentially useful for frequency standards and highresolution spectroscopy. Measurements were made of the nuclear charge radii of six stable $Ca$ isotopes. Radiofrequency transitions between excited state sublevels were studied. The nuclear quadrupole moment of the rarely encountered isotope ${}^{43}Ca$ was determined.