This technology integrates graphene surface plasmon polaritons (SPPs) with a transmission electron microscope (TEM) to produce high-quality X-rays without electron acceleration. The radiation source is compact, tunable, coherent, and highly directional; it can save millions of dollars both in operation and maintenance for academic and commercial applications, such as medical CAT scans, forensic scans, and hardware lithography.
Current methods for X-ray generation are omni-directional and not tunable because the frequencies of K-lines from the X-ray tubes are material specific. These limitations of X-ray tube technology translate to restrictions on resolution, contrast, and penetration depth in imaging applications. The drawbacks also result in longer exposure time and dangerously high radiation doses. Moreover, tube technology requires electrons to go through an acceleration stage in order to reach extremely high energies for capturing X-ray images. The aforementioned limitations restrict the development of a coherent table-top X-ray source, which could make X-rays affordable in a range of applications.
This X-ray radiation source uses extremely confined hybrid electron-photon modes called SPPs to generate coherent X-rays. SPPs are a phenomenon seen in one-atom thick materials like graphene, and function as a slowly propagating electromagnetic undulator that significantly reduces the energy threshold for electrons by a factor of 20. This invention consists of a graphene sample mounted on a dielectric slab with electrical wires to control doping levels and SPP modes. The graphene slab is positioned right underneath the TEM’s electron beam, typically where the TEM’s sample would be placed. Once the TEM is turned on, the graphene SPPs will cause the electrons to bounce, subsequently emitting X-ray radiation. The radiation source can then generate a variety of wavelengths depending on the incident electromagnetic wavelength and the SPP field.
- Affordable X-rays which require electron energies that are easily achieved using TEMs
- High-quality and high-intensity X-rays through graphene SPPs
- Compact, tunable, coherent, and highly directional X-ray radiation