Comparing TOF-SIMS with laser desorption/photoionization for surface analysis

TOF-SIMS has become the standard mass spectrometric tool for the molecular analysis of polymeric, organic, and biological surfaces. However, variations in desorption yields, ionization efficiencies, and ion-induced damage of adsorbates still present significant difficulties in the analysis of TOF-SIMS data. Laser desorption combined with photoionization may provide a significant improvement over TOF-SIMS. An instrument exists that has the capability of utilizing both methods of analysis and the potential for imaging of these surfaces. The Chicago-Argonne resonance ionization spectrometer for microanalysis (CHARISMA) is a reflection time-of-flight mass spectrometer (TOF) that is configured for secondary ion and neutral mass spectrometry using either ion beam bombardment or laser ablation for sample desorption. We have studied biotin and biotin conjugated self-assembled monolayers (SAMs) adsorbed onto gold as a model to compare the two processes