Fine-structure rotational coherent anti-Stokes Raman scattering in iron vapor.

Spontaneous and coherent Raman scattering can be used to perform atomic spectroscopy by probing the fine structure of the target atom's electronic configuration arising from spin-orbit coupling. We report the first, to the best of our knowledge, application of CARS spectroscopy to a transition metal: iron. Iron vapor is produced by laser ablation of a pure iron sample, and a tunable nanosecond CARS instrument is used to detect four Raman transitions between the fine-structure energy levels in the ground-state electronic configuration of neutral iron atoms. These results extend atomic CARS beyond previously studied chalcogens and halogen elements and enable its application to the study of metal chemistry.