Electron diffraction of CBr4 in superfluid helium droplets: A step towards single molecule diffraction

Area of Science:

• Atomic and Molecular Physics
• Condensed Matter Physics
• Materials Science

Background:

• Superfluid helium droplets offer unique ultracold environments for molecular studies.
• Diffraction background from helium droplets poses a challenge for single-molecule imaging.
• Field-induced orientation is crucial for serial diffraction but requires precise molecular alignment.

Purpose of the Study:

• To demonstrate the feasibility of electron diffraction for single molecules within superfluid helium droplets.
• To address and mitigate the diffraction background noise from helium droplets.
• To lay the groundwork for a molecular goniometer using helium droplet cooling and orientation.

Main Methods:

• Employing multiple doping with carbon tetrabromide (CBr4) to reduce undoped droplet background.
• Applying corrections for dimer and trimer species.
• Comparing experimental diffraction patterns with theoretical calculations and gas-phase data.

Main Results:

• Achieved clearly resolved CBr4 diffraction rings, comparable to gas-phase measurements.
• Experimental data aligns well with theoretical predictions and existing gas-phase results.
• Observed monomer and cluster abundances consistent with Poisson statistics.

Conclusions:

• Electron diffraction within superfluid helium droplets is a viable technique for single-molecule analysis.
• The developed method effectively reduces helium background, enabling clearer diffraction signals.
• This work is a significant step towards realizing a molecular goniometer for advanced structural studies.