Resolving the interlayer distance of cationic pyrene clusters embedded in superfluid helium droplets using electron...

Area of Science:

• Physical Chemistry
• Atomic and Molecular Physics
• Materials Science

Background:

• Investigating the structure of molecular clusters is crucial for understanding chemical bonding and material properties.
• Superfluid helium droplets offer a unique environment for trapping and studying reactive or charged species.
• Electron diffraction is a powerful technique for determining atomic-scale structures.

Purpose of the Study:

• To perform electron diffraction on cationic pyrene clusters.
• To determine structural parameters of these ionic clusters.
• To assess the feasibility of electron diffraction for ionic, all-light-atom systems.

Main Methods:

• Embedding cationic pyrene (C16H10) clusters in superfluid helium droplets.
• Performing electron diffraction on the helium droplet-embedded clusters.
• Analyzing diffraction patterns using least-squares fittings to extract structural information.

Main Results:

• Recognizable interference patterns from pyrene atomic pairs were observed despite helium's contribution.
• The interlayer distance in cationic pyrene clusters was determined to be 3.0 Å, a reduction from 3.5 Å in neutral clusters.
• The relative abundance of pyrene dimers and trimers was found to be approximately 2:1.

Conclusions:

• Electron diffraction is feasible for studying ionic all-light-atom systems, even with low particle concentrations.
• The experiment demonstrates that heavy atoms are not essential for obtaining diffraction intensity.
• Further structural details and solvation shell information were limited by experimental detection range and helium's signal dominance.