Laser-secondary neutral mass spectrometry
Laser Post-Ionization SNMS, Laser-Assisted SNMS, Laser Ionization SNMS, Post-Ionization SNMS
Laser-secondary neutral mass spectrometry (Laser-SNMS) is closely related to time-of-flight secondary ion mass spectrometry (TOF-SIMS) technology. The Laser-SNMS system combines a commercial TOF-SIMS instrument with a dedicated high-power, high-repetition-rate pulsed laser system. In this process, the material is first fragmented by the primary ion beam, releasing predominantly neutral particles. A subsequent laser pulse ionizes these neutral particles so that they can be analyzed separately. This results in a higher detection sensitivity for neutral species that are not detected in TOF-SIMS.
The ionization of the neutral sputtered particles with the laser pulse significantly increases the detection efficiency, which is advantageous for the investigation of structures in the nano range and species with low concentrations. The post-ionized particles are detected using a time-of-flight mass spectrometer. The advantage of this method is that it is not dependent on the ion yield and thus enables even more precise quantitative analysis thanks to its higher sensitivity.
However, the detection of large organic ions is challenging due to photofragmentation. The spatial resolution of Laser-SNMS is typically lower than that of TOF-SIMS because the laser pulse used for ionization covers a larger area. This results in lower spatial precision, making the method less suitable for high-resolution imaging, but it remains effective for quantitative elemental analysis on smaller areas.
Laser SNMS is used in applications where precise quantitative information about elemental composition is important, such as in geochemistry, materials research, and isotopic analysis. Its ability to detect neutral species makes it a powerful method for analyzing elements that are difficult to ionize and for investigating samples with a strong matrix effect.
TOF-SIMS is particularly suitable for qualitative chemical surface analysis and imaging, while laser SNMS offers higher sensitivity for neutral atoms and is particularly suitable for precise quantitative analysis.