Different mechanisms of impulsive optical spin orientation in paramagnetic and diamagnetic copper (II) complexes

Impulsive optical spin orientation has been observed directly by a pick-up-coil detection in copper (II)-acetate in water, acetic acid, and solids. Difference in the dependences of the signal intensity and relaxation time on the excitation polarization, external magnetic field, and temperature reveals two origins of the optical spin orientation: one due to angular-momentum transfer from a circularly polarized light and the other from the photo-creation of a Zeeman-mixed state under the external magnetic field.