This field also affects the gas-phase molecules in the vicinity of the jet. Whereas in the gas-phase experiment the vacuum level of the gas matches that of the analyzer, in the aqueous solution experiment the vacuum level of the gas is pinned to the vacuum levels of the liquid and of the analyzer, which results in an electric field between the two (depicted as sloped energy levels of the gas). The Fermi levels of the jet and the analyzers match by design (they are both grounded), but their vacuum levels do not because of the difference in the respective workfunctions. Reproduced from Ref. 12 with permission from the Royal Society of Chemistry.