New probe for the secrets of complex interfaces

January 22, 2019, US Department of Energy
Scientists have devised a spectroscopy method—based on soft X-ray second-harmonic generation—that probes buried graphene layers inside graphite. Credit: US Department of Energy

In rechargeable batteries, ultra-thin material sheets are crucial. Reactions occur at the interfaces of these sheets. Scientists want to track these reactions. They need a way to probe buried interfaces with elemental specificity. In principle, soft X-ray spectroscopy techniques could be a powerful tool for probing such complex interfaces. However, these techniques haven't been available due to limitations in optics and laser sources. For the first time, an international team devised a soft X-ray second harmonic generation technique and used it to characterize individual layers of graphene inside a graphite sample, promising to open new vistas into the nature of complex interfaces.

Knowing how reactions occur at buried interfaces is crucial for , water purification, and other uses. The new technique offers a way to probe specific elements at buried interfaces. The results from the technique could, one day, let scientists use soft X-rays to track interfacial processes occurring in a quadrillionth of a second.

Understanding the detailed nature of complex interfaces has become a quest of profound significance, as it underlies urgently needed advances in many applications, including , desalination, and reclamation technologies, and is vital to central processes in electrochemistry, atmospheric chemistry, biochemistry, and energy conversion. Scientists developed a new technique to probe interfaces with both surface and element-specific selectivity, demonstrated for the individual graphene layers within bulk graphite. When soft X-ray pulses from a enter the material, they excite inner-orbital electrons in the . For carbon atoms making up a graphite interface, these excitations can produce a photon (a packet of light) with twice the energy of the incoming photons. Scientists can use observations of this second harmonic generation to elucidate important interfacial properties, as well as chemical reactions occurring on these interfaces.

Explore further: Oxygen migration at the heterostructure interface

More information: R. K. Lam et al. Soft X-Ray Second Harmonic Generation as an Interfacial Probe, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.120.023901

Related Stories

Oxygen migration at the heterostructure interface

January 11, 2019

NUS physicists have developed a methodology to control the electromigration of oxygen atoms in the buried interfaces of complex oxide materials for constructing high mobility oxide heterostructures.

New electron glasses sharpen our view of atomic-scale features

September 6, 2018

What if we could make a powerful scientific tool even better? Atom probe tomography (APT) is a powerful way of measuring interfaces on a scale comparable to the distance between atoms in solids. It also has a chemical sensitivity ...

Photoelectrodes revealed

August 8, 2016

To turn intermittent solar energy into transportable chemical fuels, scientists are investigating a key junction inside designer photoelectrochemical cells. The junction forms between two materials: the layer that absorbs ...

Imaging accumulated charges at solid-electrolyte interfaces

October 2, 2018

Charges and their transport are integral to the function of electronic devices, batteries, and biological systems. The charges that accumulate at the interface between a solid electrode and an electrolytic solution containing ...

Recommended for you


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.