SECONDARY EMISSION MASS SPECTROMETER

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We have initiated a systematic study of the energetics of various organic ions in relation to the different experimental conditions ion SIMS and FAB analysis. Knowledge of the energy distribution (ED) of secondary organic ions helps us to understand the mechanism of organic sputtering and provides information for the optimization of liquid SIMS. Based on our previous data, we proposed that the primary mechanism responsible for the emission of secondary organic ions is linear cascade sputtering, as this process results in the production of ions with lower kinetic energy. A major accomplishment in this FY was development - in collaboration with Teknivent. Inc. - of a data system based on an IBM PC-XT (256K), which was designed to control the quadrupole mass spectrometer of the SEMS system, and to scan the energy of secondary ions to produce energy distributions N(E)= f(E). The computer system was used to scan the main cylinder voltage (Vm) of the electrostatic energy analyzer (Bessel Box) as well as to control the tandem quadrupole mass spectrometer. The target bias (Vt) remained fixed during the energy scan, and the energy distribution was determined as a function of ion intensity versus (Vm-Vt). Complete spectra were stored for each step of the energy scan. We have studied the energy distribution of secondary organic ions of arginine as well as effects of various liquid matrices on this parameter. Matrices employed included glycerol, triethanolamine, triethylglycol, and polyethyleneglycols, as well as protonating systems such as trifluoromethanesulfonic acid (TFMSA) and tartaric acid (TA).