  The scattering of a Dirac particle has been studied for a quaternionic
potential step. In the potential region an additional diffusion solution is
obtained. The quaternionic solution which generalizes the complex one presents
an amplification of the reflection and transmission rates. A detailed analysis
of the quaternionic spinorial velocities sheed new light on the additional
solution. For pure quaternionic potentials, the interesting and surprising
result of total transmission is found. This suggests that the presence of pure
quaternionic potentials cannot be seen by analyzing the reflection or
transmission rates. It has be observed by measuring the mean value of some
operator.
