Fragmentation pathways of tungsten hexacarbonyl clusters upon electron ionization

Area of Science:

• Physical Chemistry
• Materials Science
• Surface Science

Background:

• Tungsten hexacarbonyl (W(CO)6) is vital for nanofabrication via electron beam and ion beam induced deposition.
• Understanding the ionization and fragmentation of W(CO)6 clusters is key to optimizing these deposition techniques.

Purpose of the Study:

• To investigate the electron ionization of neat tungsten hexacarbonyl clusters.
• To characterize the resulting positive ion mass spectra and fragmentation patterns.
• To estimate appearance energies for dissociative ionization channels.

Main Methods:

• Crossed electron-molecular beam experiment.
• Mass spectrometry.
• Electron ionization at 70 eV.
• Analysis of ion efficiency curves.

Main Results:

• Observed ion series: W(CO)n+ (0 ≤ n ≤ 6), W2(CO)n+ (0 ≤ n ≤ 12), WC(CO)n+ (0 ≤ n ≤ 3), and W2C(CO)n+ (0 ≤ n ≤ 10).
• Distinct changes in fragment ion intensity for clusters compared to single molecules.
• Fragmentation patterns explained by sequential decay of ionized organometallic species.
• Estimated appearance energies for singly charged ions.

Conclusions:

• Electron ionization of W(CO)6 clusters produces characteristic fragmentation patterns.
• Cluster-specific fragmentation differs significantly from single-molecule behavior.
• The study provides fundamental insights into the behavior of W(CO)6 under electron ionization, relevant for nanofabrication.