Figure 1.
Crystal structure of Li2O2, Li2CO3, and Li2O.
Red (largest) spheres represent oxygen atoms, green (smaller) spheres represent lithium atoms and purple (smallest) spheres are carbon atoms. Li-O polygons are drawn for better view.
Figure 2.
Li K-edge XAS spectra of Li2O2, Li2CO3, and Li2O.
Figure 3.
O K-edge XAS spectra of Li2O2, Li2CO3, and Li2O.
Figure 4.
Soft x-ray irradiation effect on Li2O2 revealed by Li K-edge XAS spectra.
(top) The XAS spectrum of Li2O2 evolves towards that of the Li2O upon increasing the radiation exposure. The top spectrum is the first one collected from spot A. From top to bottom, the first ten spectra were collected every ten minutes, with an hour of x-ray exposure at the same spot to maximize the dosage, then the measurements resumed with again ten minute each spectrum. The bottom red spectrum is collected on Li2O for comparison. (bottom) Li2O2 Li K-edge XAS spectrum measured from a new spot B on the same sample stored in the ultra-high vacuum chamber for one week.
Figure 5.
Soft x-ray irradiation effect on Li2CO3 revealed by Li K-edge XAS spectra.
The XAS lineshape of Li2CO3 (from top to bottom) evolve towards that of Li2O (red) after exposed to the soft x-rays. Each spectrum was taken with 10 minute x-ray exposure. The bottom panel shows the Li2CO3 Li K-edge XAS spectrum collected from a new spot B on the same sample.
Figure 6.
Li K-edge XAS spectra of Li2O.
The spectra were collected on fresh surface, the same spot with 0.5 hour soft x-ray exposure, and 12 hours of soft x-ray exposure.