Laser-magnetic-resonance detection of magnesium atoms in the metastable³p_{0, 1, 2} states

Transitions between fine-structure levels of the metastable (3s3p3P) state of magnesium have been observed by means of the highly sensitive technique of far-infrared laser-magnetic-resonance spectroscopy. The g factors for the 3Pi and 3P2 levels are 1.50111(16) and 1.50102(16), respectively, and the 3Pi-3P2 energy separation is 1 220 575.1(33) MHz. The observed g factors show good agreement with the predicted values. This stands in marked contrast to similar results for atomic silicon (3P) and aluminum (2P), for which the theoretical and experimental g factors differ substantially. The value of the 3Pi-3P2 energy separation is improved by nearly 2 orders of magnitude over the optical value and is of sufficient accuracy to permit possible extraterrestrial identification.