  Using low energy Time-of-Flight Scattering and Recoil Spectroscopy (TOF-SARS)
and Mass Spectroscopy of Recoiled Ions (MSRI) we analyze the surface structure
of an atomically smooth BaBiO$_3$ film grown by molecular beam epitaxy. We
demonstrate high sensitivity of the TOF-SARS and MSRI spectra to slight changes
in the orientation of the ion scattering plane with respect to the
crystallographic axes. The observed angle dependence allows us to clearly
identify the termination layer as BiO$_2$. Our data also indicate that
angle-resolved MSRI data can be used for high resolution studies of surface
structure of complex oxide thin films.
