  We present a comprehensive study of the diverse properties of heteronuclear
Rydberg molecules, placing a special emphasis on those composed of the light
alkali atoms, Li, Na, and K. Electron-atom scattering phase shifts, which
determine the strength of the molecular bond, are calculated at very low energy
and then used in a spin-dependent theoretical model to calculate accurate
Rydberg molecule potential energy curves. The wide parameter range accessible
by combining the various properties of different alkali atoms often leads to
hybridized electronic states accessible via one or two photon excitation
schemes. This analysis of heteronuclear molecules leads to a prediction that
the relative densities and spatial distributions of atoms in an ultracold
mixture can be probed at controllable length scales via spectroscopic detection
of these molecules.
