The role of net angular momentum in pump/probe spectroscopy: Absorption, refringence, scattering, and nuclear resonance
Applied net angular momentum ( J) has the same role in spectroscopy as applied magnetic flux density ( B), both having the same parity and motion reversal symmetry. This simple statement appears to have profound consequences, especially in the context of nonlinear optics, where J can be generated by a pump laser. These properties are explored for pump/probe spectroscopy involving absorption, refringence, and scattering in the semiclassical Rayleigh theory. It is shown that there are phenomena analogous to those induced by B, exemplified by the spin chiral class of circular and axial birefringence/dichroism (analogues of the Faraday and Wagnière/Meier effects produced by B); and pump-laser-induced Rayleigh/Raman optical activity; analogues of scattered optical activity induced by B. Nuclear effects of the pump-laser-induced J are introduced as nuclear electromagnetic resonance (NER).