This is a proposal to fully characterise the crystal structures of the superconducting metal/ammonia intercalates of FeSe made using low temperature methods. In particular we will establish the compositions and detailed crystal structures of the high temperature superconductors (Tc = 30-40 K) obtained when tetragonal FeSe reacts with Rb and solutions of the ammonia-soluble alkaline earths. The use of neutrons in concert with X-rays will enable us to locate light N and D atoms of intercalated ammonia molecules.