Tetrahedral hydrocarbon nanoparticles in space: X-ray spectra
  It has been proposed, or confirmed, that diamond nanoparticles exist in
various environments in space: close to active galactic nuclei, in the vicinity
of supernovae and pulsars, in the interior of several planets in the Solar
system, in carbon planets and other exoplanets, carbon-rich stars, meteorites,
in X-ray active Herbig Ae/Be stars, and in the interstellar medium. Using
density functional theory methods we calculate the carbon K-edge X-ray
absorption spectrum of two large tetrahedral nanodiamonds: C26H32 and C51H52.
We also study and test our methods on the astrophysical molecule CH4, the
smallest C-H tetrahedral structure. A possible detection of nanodiamonds from
X-ray spectra by future telescopes, such as the project Arcus, is proposed.
Simulated spectra of the diffuse interstellar medium using Cyg X-2 as a source
show that nanodiamonds studied in this work can be detected by Arcus, a high
resolution X-ray spectrometer mission selected by NASA for a Phase A concept
study.
