Gold nanoparticles exposed

 

Switzerland-based researchers have used ultrafast electron diffraction to provide new insight to the structures of gold nanoparticle supracrystals.

 

Determining the local arrangement of structures within these functional nanoparticles will prove crucial to the use of nano-assembled materials in medicine, biology, solar cells and more.

 

While understanding the structure of gold nanoparticle supracrystals is critical to the design of  functional nanoparticles, researchers have struggled to resolve data on the ligand molecules within. 

 

With this in mind, Professor Fabrizio Carbone from EPFL, and colleagues, developed femtosecond small-angle time-resolved electron diffraction to determine the local arrangement of these structures from nanometre to interatomic scales.

 

As part of past research, they had developed a cheap alternative to the free electron laser.

 

A billion dollar free electron laser uses electrons to generate ultra-short X-ray pulses to determine molecular structures at an atomic scale.

 

However, Carbone's tabletop version creates electron bunches that can be controlled and focused with electric fields, producing an electron beam for structural analysis.

 

"This novel device is based on the recent insight that the Coulomb explosion of electron bunches in the 100 keV range, can be made fully reversible by tailoring the spatial distribution of the bunch charge," explains Carbone. "[This enables] single-shot measurements and sub-100 fs resolution."

 

Using the 'cheap FEL', the researchers developed a small-angle time-resolved electron diffractometer, which they claim can analyse dense aggregates and small molecules with the same sensitivity as X-ray diffraction, using a traditional FEL, but at a fraction of the cost.

 

Using this approach, the researchers imaged light-activated structural changes in the functionalised gold nanoparticles at atomic resolution.

 

 

Experiments revealed that ligand molecules attached to gold nanoparticles can self-assemble and order in preferential orientations, critical information for researchers creating ordered nanostructures.

 

According to Carbone and colleagues, discovering that light induces this ordering phenomena, points to a unique tool for controlling the physics of gold nanoparticles with potential for optoelectronic applications.

 

"The study provides proof-of-concept evidence that the small-angle time-resolved electron diffractometer enables the systematic investigation of structural properties of nano-assembled materials," concludes Carbone.

 

Research is published in NanoLetters.