Dynamic Reactive Ionization with Cluster Secondary Ion Mass Spectrometry

Area of Science:

• Analytical Chemistry
• Surface Science
• Materials Science

Background:

• Gas cluster ion beams (GCIB) are used for secondary ion mass spectrometry (SIMS) and molecular imaging.
• Previous work enhanced ionization by doping Ar clusters with CH4, CO2, and O2.

Purpose of the Study:

• To investigate enhancing ionization by doping Ar clusters with HCl.
• To explore the synergistic effect of HCl doping and water on target surfaces.

Main Methods:

• Forming mixed Ar-HCl clusters for GCIB.
• Depth profiling of trehalose thin films with D2O vapor.
• Monitoring H-D exchange in trehalose using mass spectrometry.

Main Results:

• HCl doping in Ar clusters, combined with surface water, increased protonated molecules ~20-fold.
• Optimal ionization conditions were maintained by adjusting water vapor pressure.
• Observed H-D exchange in trehalose molecules, indicating successful deuterium incorporation.

Conclusions:

• HCl-doped GCIB with surface water effectively enhances secondary ion yields.
• Surface chemistry and dynamic reactive ionization are crucial for increasing ion yield.
• This technique expands SIMS applications for molecular imaging.