"The terahertz (THz) band of the spectrum remained unexplored until recent years. New techniques and devices have been developed to analyze THz emission from several sources. THz emission spectroscopy opened a new window to study carrier dynamics in semiconductors with a temporal resolution of a few femtoseconds. This thesis presents a series of experiments to attempt to detect the THz radiation emitted when carriers are optically excited with circularly polarized light; since the optical orientation and spin relaxation transient is expected to emit a THz electric pulse. The theoretical basis of spintronics and the fundamental mechanisms involved during optical orientation and spin relaxation are presented in order to understand the mechanisms involved in spin transients. Semiconductors can generate THz radiation by a variety of processes that occur simultaneously depending on the semiconductor properties; and these effects are also explained. An initial proposal for the temporal profile of the THz radiation emitted by the changing magnetic moment is presented. The previous THz experiments leading to this thesis are also reviewed. The THz emission spectroscopy technique used for this thesis and the detection devices available to date are described. Finally, the experimental effort to find the spin THz emission is presented. The experimental setup is explained and the obtained measurements are studied. Power modulation of the pump beam, caused by the Liquid Crystal Retarder, was found and corrected for. The final measurement does not show the spin THz radiation, it is concluded that it might be smaller than expected."