Soft-x-ray emission and absorption study of the quasi-one-dimensional oxide conductors K0.3MoO3 and Li0.9Mo6O17

We have studied the electronic structure of the quasi-one-dimensional conductors K0.3MoO3 and Li0.9Mo6O17 as well as the related insulating compound MoO3 using x-ray emission and absorption spectroscopy. From the O K spectra we derive a picture of the oxygen partial density of states and assign the features in the spectra to corresponding bands from a molecular-orbital picture. X-ray emission and absorption spectra each show two distinct structures that are related to the occupied pi and sigma bands and unoccupied pi* and sigma* bands, respectively. Large anisotropies in the x-ray absorption spectra of the quasi-one-dimensional crystal K0.3MoO3 are found, whereas Li0.9Mo6O17 shows only very little anisotropy. We also investigated the effect of air exposure to the O K absorption edge K0.3MoO3 and find that the out-of-plane bonds are significantly affected, whereas the in-plane bonds appear rather insensitive to contamination.