Developing repeatable measurements for reliable analysis of molecules at surfaces using desorption electrospray...

Area of Science:

• Analytical Chemistry
• Surface Science
• Mass Spectrometry

Background:

• Desorption electrospray ionization (DESI) is a key ambient ionization technique for direct surface analysis.
• Limited research exists on DESI's fundamental parameters and metrology, hindering industrial adoption.
• Understanding these factors is crucial for developing DESI into a reliable technique.

Purpose of the Study:

• To systematically investigate parameters influencing DESI repeatability, sensitivity, and material consumption.
• To develop and utilize a model sample for optimizing DESI performance.
• To elucidate the electrospray-sample interaction and desorption mechanisms.

Main Methods:

• Development of a model sample: a thin, uniform Rhodamine B film on glass.
• Systematic study of parameters affecting DESI performance (repeatability, sensitivity, material consumption).
• Confocal microscopy to analyze droplet distribution, material utilization, and spot size.

Main Results:

• Optimized DESI parameters achieved absolute intensity repeatability better than 15% over 1 day.
• The model sample enabled detailed study of electrospray-sample interactions and desorption.
• Surface erosion rates were determined, analogous to sputtering yield.

Conclusions:

• The study provides a clear understanding of how electrospray parameters affect DESI performance.
• Optimization led to improved spatial resolution and sensitivity.
• The developed model sample and methodology advance DESI for industrial applications.