Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Materials Science

Background:

• Matrix-assisted laser desorption/ionization (MALDI) is a key technique for analyzing large molecules.
• Understanding primary ion formation in laser desorption/ionization (LDI) is crucial for optimizing MALDI.
• Fullerene-C60 serves as a model analyte for studying fundamental ionization processes.

Purpose of the Study:

• To investigate the influence of target plate materials on fullerene-C60 ion formation in LDI.
• To elucidate the mechanisms and time frames of primary ionization in (MA)LDI.
• To identify substrate properties that enhance ion signal intensity for more sensitive mass spectrometry.

Main Methods:

• Systematic laser desorption/ionization (LDI) experiments using fullerene-C60 on various target plate materials.
• Monitoring positive and negative ion signal intensities of precursor, fragment, and cluster ions.
• Varying laser fluence and ion extraction delay times to study ionization dynamics.

Main Results:

• Increasing electrical resistivity of target materials enhances fullerene-C60 precursor and fragment anion signals.
• Highly resistive materials (Inconel 625, Ti90/Al6/V4) yielded the highest anion intensities.
• A mechanism involving transient electrical field strength reduction was proposed to explain anion enhancement.
• Cluster cation formation was observed, but precursor and fragment cations dominated at high fluences.

Conclusions:

• Substrate material choice critically affects ion signal intensity in LDI.
• Optimizing target plate materials can lead to significantly more sensitive (MA)LDI measurements.
• The findings provide fundamental insights into primary ionization mechanisms in (MA)LDI.