  We report on an experimental investigation of rapid adiabatic passage (RAP)
in a trapped barium ion system. RAP is implemented on the transition from the
$6S_{1/2}$ ground state to the metastable $5D_{5/2}$ level by applying a laser
at 1.76 $\mu$m. We focus on the interplay of laser frequency noise and laser
power in shaping the effectiveness of RAP, which is commonly assumed to be a
robust tool for high efficiency population transfer. However, we note that
reaching high state transfer fidelity requires a combination of small laser
linewidth and large Rabi frequency.
