Our recent work on the behavior of water molecules adsorbed on a Pt emitter tip in high fields (~1 V/ Å) has provided an understanding of the behavior of water dissociation and ion cluster [H@super +@(H@sub 2@O)@sub n@] emission. Water ion emission from an emitter tip has traditionally been treated as a single step event. While differing n cluster types have been observed, typically ranging to 10 or above, no detailed explanation of the mechanism for cluster formation has been suggested. Mass resolved ramped field desorption experiments from field adsorbed water layers (T>170K) have given field dependencies for specific ion cluster masses. As the field was ramped, each cluster type was observed, in turn, beginning with high n clusters and transitioning to lower n clusters. The emission of high n clusters was energetically favored, while low n clusters were favored kinetically. However, at low temperatures (T<150K), all observed ions appeared simultaneously at a critical onset field as the tip potential was ramped, demonstrating a common limiting reaction step. This ion burst contained only those clusters observed in the field adsorbed work at the onset field or below. Constant field, temperature cycled ion emission experiments have given solvation energies for protons resident in the surface adsorbed layer. Spatially resolved field ion microscopy of the ion cluster emission has shown localization of the ion emission event. These results have lead us to suggest a 2 step mechanism for ion emission, where dissociation is a distinctly separate event from desorption of the ion cluster. At low temperatures the dissociative ionization event is rate limiting, while at higher temperatures dissociation occurs freely, making the ion cluster emission the rate determining step.