  It is shown that a single molecular magnet placed in a rapidly oscillating
magnetic field displays the phenomenon of quenching of tunneling processes. The
results open a way to manipulate the quantum states of molecular magnets by
means of radiation in the terahertz range. Our analysis separates the time
evolution into slow and fast components thereby obtaining an effective theory
for the slow dynamics. This effective theory presents quenching of the tunnel
effect. In particular, stands out its difference with the so-called coherent
destruction of tunneling. We support our prediction with numerical evidence
based on an exact solution of the Schr\"odinger's equation.
