Gold-Assisted Molecular Imaging of Organic Tissue by MeV Secondary Ion Mass Spectrometry

The quality of molecular imaging by means of MeV primary ion-induced secondary ion mass spectrometry by coating with gold was evaluated on different reference organic molecules and plant samples. The enhancement of the secondary ion yield was evident for the majority of the studied analytes, reaching the highest values at gold thicknesses between 0.5 and 2 nm, and increased the intensity up to 5-fold for reference samples and >2-fold for specific peaks within the plant sample. Improved propagation of the electric field due to the target potential on otherwise electrically insulating plant samples was also evident through improved image resolution and by reducing the background in mass spectra. However, detection of several molecules was significantly decreased at even at 1 nm thick gold layer. The results indicated that an optimized sequence of analysis is required to reliably interpret results.