Far-UV-Excited Luminescence of Nitrogen-Vacancy Centers: Evidence for Diamonds in Space.

The nitrogen-vacancy (NV) centers in diamond are among the most thoroughly investigated defects in solid-state matter; however, our understanding of their properties upon far-UV excitation of the host matrix is limited. This knowledge is crucial for the identification of NV as the carrier of extended red emission (ERE) bands detected in a wide range of astrophysical environments. Herein, we report a study on the photoluminescence spectra of NV-containing nanodiamonds excited with synchrotron radiation over the wavelength range of 125-350 nm. We observed, for the first time, an emission at 520-850 nm with a quantum yield greater than 20 %. Our results share multiple similarities with the ERE phenomena, suggesting that nanodiamonds are a common component of dust in space.