Resonant X-ray Emission and Valence-band Lifetime Broadening in LiNO${}_3$

Abstract

X-ray absorption and resonant inelastic x-ray scattering measurements are carried out on lithium nitrate LiNO${}_3$. The $\sigma$ orbitals around the nitrogen atoms exhibit a large lifetime effect. Experimentally, this is manifest as an apparent weakening of the x-ray emission signal from these states, but a closer examination shows that instead it is due to extreme broadening. This echos previous studies on ammonium nitrate, which, despite large differences in the cation and space group, showed a similar effect associated with the nitrate. Using first-principles $GW$ self-energy and Bethe-Salpeter equation calculations we show that this effect is due in part to short quasi-hole lifetimes for the orbitals constituting the NO $\sigma$ bonds.