Having confirmed that 𝑄 𝐼𝐼 𝑃 lipid films are aligned along the [100] direction perpendicular to the substrate, the orientations of cubic lipid films are further assigned by imaging the terminating surface structure with atomic force microscopy under bulk water. By utilizing peak force tapping AFM, in which the force exerted by the AFM probe is known and finely controlled , highresolution images of the surface of the 𝑄 𝐼𝐼 𝑃 phase film are readily obtained (Figure ). Images of the surface structure reveal a square lattice with the same orientation as those measured by GI-SAXS, with the cubic lattice aligned along the (100) facet, i.e. with the (100) plane in the plane of the image. In addition, AFM uncovers the grain boundaries contained within the cubic film, as disclinations between domains with different in-plane orientations (Figure ), confirming the rotationally averaged polydomain nature of the sample suggested from the GI-SAXS analysis (Figure and Figure ).