  The $\gamma n \to \pi^- p$ and $\gamma p \to \pi^+ n$ reactions are essential
probes of the transition from meson-nucleon degrees of freedom to quark-gluon
degrees of freedom in exclusive processes. The cross sections of these
processes are also advantageous, for the investigation of oscillatory behavior
around the quark counting prediction, since they decrease relatively slower
with energy compared with other photon-induced processes. In this talk, we
discuss recent results on the $\gamma p \to \pi^+ n$ and $\gamma n \to
\pi^{-}p$ processes from Jefferson Lab experiment E94-104. We also discuss a
new experiment in which singles $\gamma p \to \pi^+ n$ measurement from
hydrogen, and coincidence $\gamma n \to \pi^{-} p$ measurements at the
quasifree kinematics from deuterium for center-of-mass energies between 2.3 GeV
to 3.4 GeV in fine steps at a center-of-mass angle of $90^\circ$ are planned.
The proposed measurement will allow a detailed investigation of the oscillatory
scaling behavior in photopion production processes.
