Observation of Cerenkov radiation with a photon energy of 284 eV
Bazylev V. A., Glebov V. I., Denisov E. I., Zhevago N. K., Khlebnikov A. S., Tsinoev V. G., Chertov Yu. P., Shramenko B. I.
Cerenkov radiation by relativistic electrons has been observed in amorphous carbon near its К absorption edge. The real part of the dielectric constant of carbon is confirmed to be greater than unity near 284 eV.