MOSCOW, August 15. /TASS/ Physicists from the Moscow Institute of Physics and Technology (MIPT) have shown graphene to be a suitable material for manufacturing plasmonic devices capable of detecting explosive materials, toxic chemicals, and other organic compounds based on a single molecule, as reported by the press service of MIPT. The results of the study have been published in the Physical Review B.
Plasmons are quanta of plasma oscillations appearing at the metal surfaces when exposed to the light. Space, where the wave of plasmonic oscillations propagates, is smaller than the wavelength and therefore the plasmonic oscillations do not envelope even the smallest irregularities on the metal surfaces but instead they run against the defects. This implies that the plasmons can be used to disclose even the single molecules, as suggested by the MIPT researches. Unfortunately, plasmons have a drawback, and namely, the plasmonic oscillations on the metal surface damp very quickly.
The researchers have solved the problem by the switch to graphene. Graphene is a two-dimensional crystal, an allotrope modification of carbon (as diamond or graphite) but absolutely planar and consisting of only one layer of carbon atoms. Graphene has attracted an attention because of its extremely high conductivity and hence possibility to replace metals for creating plasmonic oscillations and to maintain ultra-sensitive sensors.
The scientists from MIPT has created a model describing plasmonic behaviour on the graphene surface and developed the concept of surface plasmon laser (SPASER, the surface plasmon amplification by stimulated emission of radiation) using a graphene layer.
SPASER can be described as a device similar to an ordinary laser by its working principle, but the surface plasmon is generated instead of usual electromagnet wave. The device will operate in the infrared region where the biological molecules are normally investigated.