Dependence of MeV TOF SIMS secondary molecular ion yield from phthalocyanine blue on primary ion stopping power

Time-of-flight Secondary Ion Mass Spectrometry (TOF SIMS) is a well-established mass spectrometry technique used for the chemical analysis of both organic and inorganic materials. In the last ten years, many advances have been made to improve the yield of secondary molecular ions, especially those desorbed from the surfaces of organic samples. For that, cluster ion beams with keV energies for the excitation were mostly used. Alternatively, single-ion beams with MeV energies can be applied, as done in the present work. It is well known that secondary molecular/ion yield depends strongly on the primary ion stopping power, but the nature of this dependence is not completely clear. Therefore, in the present work secondary ion yield from the phthalocyanine blue (C₃₂H₁₆CuN₈, organic pigment) was measured for the various combinations of ion masses, energies and charge states. Measured values were compared with the existing models for ion sputtering. An increase of the secondary yield with the primary ion energy, electronic stopping, velocity and charge state was found for different types of primary ions. Although this general behavior is valid for all primary ions, there is no single parameter that can describe the measured results for all primary ions at once.  

- measured (calibrated) spectra are uploaded