Enhancement of ion evaporation by the CO2 laser irradiation on the electrospray and ion spray

Ion evaporation induced by the CO2 laser (10.6 mu m) irradiation on the ion spray and electrospray was studied. When the tip of the Taylor cone of the electrospray for the solution of decamethylenediamine was irradiated by the focused CO2 laser beam, the strong growth of the (M + 2H)(2+) ion was observed while the intensity of (M + H)(+) stayed nearly constant. In contrast, the intensity of the (M + H)(+) ion showed much stronger increase than that of (M + 2H)(2+) when the ion spray using SF6 containing N-2 nebulizer gas was irradiated by CO2 laser. The increase of the ion intensities by the irradiation of the electrospray Taylor cone was found to be nearly the same for all the alkali ions, Li+, Na+, K+, Rb+ and Cs+ ions. These experimental results are interpreted on the grounds of free energy changes for the evaporation of solvated ions from the bulk solution to the gas phase. (C) 1997 Elsevier Science B.V.