  We load a Bose-Einstein condensate into a one-dimensional (1D) optical
lattice altered through the use of radiofrequency (rf) dressing. The rf
resonantly couples the three levels of the $^{87}$Rb $F=1$ manifold and
combines with a spin-dependent "bare" optical lattice to result in adiabatic
potentials of variable shape, depth, and spatial frequency content. We choose
dressing parameters such that the altered lattice is stable over lifetimes
exceeding tens of ms at higher depths than in previous work. We observe
significant differences between the BEC momentum distributions of the dressed
lattice as compared to the bare lattice, and find general agreement with a 1D
band structure calculation informed by the dressing parameters. Previous work
using such lattices was limited by very shallow dressed lattices and strong
Landau-Zener tunnelling loss between adiabatic potentials, equivalent to
failure of the adiabatic criterion. In this work we operate with significantly
stronger rf coupling (increasing the avoided-crossing gap between adiabatic
potentials), observing dressed lifetimes of interest for optical lattice-based
analogue solid-state physics.
