Analysis of native biological surfaces using a 100 kV massive gold cluster source

In the present work, the advantages of a new, 100 kV platform equipped with a massive gold cluster source for the analysis of native biological surfaces are shown. Inspection of the molecular ion emission as a function of projectile size demonstrates a secondary ion yield increase of ∼100× for 520 keV Au ₄₀₀ ⁴⁺ as compared to 130 keV Au ₃ ¹⁺ and 43 keV C ₆₀. In particular, yields of tens of percent of molecular ions per projectile impact for the most abundant components can be observed with the 520 keV Au ₄₀₀ ⁴⁺ probe. A comparison between 520 keV Au ₄₀₀ ⁴⁺ time-of-flight-secondary ion mass spectrometry (TOF-SIMS) and matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) data showed a similar pattern and similar relative intensities of lipid components across a rat brain sagittal section. The abundant secondary ion yield of analyte-specific ions makes 520 keV Au ₄₀₀ ⁴⁺ projectiles an attractive probe for submicrometer molecular mapping of native surfaces.