A collaboration between the A*STAR Singapore Institute of Manufacturing Technology (SIMTech) and the Massachusetts Institute of Technology (MIT) in the United States has proposed a versatile, directional graphene-based X-ray source that potentially could fit on a laboratory bench.

An X-ray source that is both small and powerful is a highly desirable concept. The researchers wanted to create something that is compact and also capable of producing very intense X-rays, essentially implementing the concept behind the enormous free-electron-laser sources on a scale small enough to fit on a laboratory table or even a microchip. For this purpose, the team utilized graphene's ability to support plasmons — collections of electronic oscillations that can be used to confine and manipulate light on scales of around ten nanometers. The scientists explain that Graphene plasmons are a natural option because they are capable of confining electromagnetic radiation to very small scales.

According to the team, one standout characteristic of such a source will be its directionality, or ‘pointability’, which will increase efficiency and hence lower costs by ensuring that all the generated radiation goes where it is supposed to. This will make the source promising for medical treatments as it could be used to target tumors more precisely and hence minimize damage to surrounding organs and cells. Also, a very attractive point will be the source’s versatility. The output radiation frequency can be tuned in real time from longer infrared rays to shorter X-rays by modifying various elements of the source, such as the speed of the electrons, the frequency of the graphene plasmons and the conductivity of the graphene.

This flexible, compact source is promising as a cost-effective alternative to the high-intensity beams used for fundamental scientific and biomedical research. While there is still a long way to go to actual realization, this seems to be a very exciting research direction. Next, the team plans to experimentally verify their concept with proof-of-principle trials.