Attractive electron-electron interaction due to the molecular tunneling modes in a metal-ammonia mixture

The contribution of virtual exchange of vibrational molecular excitations to an effective electron-electron attraction in a metal-ammonia mixture is estimated. Within the approximations used, the exchange of vibrational modes in the infrared gives a negligibly small attraction. The inversion level gives an attraction which generally gives much too weak an interaction to lead to superconductivity but might, under exceptionally favorable circumstances, give a superconducting Tc as large as 1°K.