Polarization dependence of x-ray absorption spectra in graphene

Abstract

We calculate the x-ray absorption spectra (XAS) for $1s$-${\ensuremath{\pi}}^{*}$ and $1s$-${\ensuremath{\sigma}}^{*}$ transitions in single layer graphene using the dipole approximation and we compare with experimental results. It is found that the in-plane and out-of-plane orientations of the dipole vectors, which correspond to the $1s$-${\ensuremath{\pi}}^{*}$ and $1s$-${\ensuremath{\sigma}}^{*}$ transitions, respectively, are responsible for the polarization dependence of the x-ray absorption intensity in graphene. Using the atomic matrix elements, the low-energy XAS peaks can be assigned.