Mass spectrometric imaging of brain tissue by time-of-flight secondary ion mass spectrometry--How do polyatomic primary beams C₆₀⁺, Ar₂₀₀₀⁺, water-doped Ar₂₀₀₀⁺ and (H₂O)₆₀₀₀⁺ compare?

Rationale: To discover the degree to which water-containing cluster beams increase secondary ion yield and reduce the matrix effect in time-of-flight secondary ion mass spectrometry (TOF-SIMS) imaging of biological tissue.

Methods: The positive SIMS ion yields from model compounds, mouse brain lipid extract and mouse brain tissue together with mouse brain images were compared using 20 keV C60(+), Ar2000(+), water-doped Ar2000(+) and pure (H2O)6000(+) primary beams.

Results: Water-containing cluster beams where the beam energy per nucleon (E/nucleon) ≈ 0.