  The misfit oxide, Bi$_{2}$Ba$_{1.3}$K$_{0.6}$Co$_{2.1}$O$_{y}$, made of
alternating rocksalt-structured [BiO/BaO] layers and hexagonal CoO$_{2}$
layers, was studied by angle-resolved photoemission spectroscopy. Detailed
electronic structure of such a highly strained oxide interfaces is revealed for
the first time. We found that under the two incommensurate crystal fields,
electrons are confined within individual sides of the interface, and scattered
by umklapp scattering of the crystal field from the other side. In addition,
the high strain on the rocksalt layer raises its chemical potential and induces
large charge transfer to the CoO$_{2}$ layer. Furthermore, a novel interface
effects, the interfacial enhancement of electron-phonon interactions, is
discovered. Our findings of these electronic properties lay a foundation for
designing future functional oxide interfaces.
