| Nonresonant inelastic x-ray scattering (NIXS) is rapidly growing as an alternative to and extension of x-ray absorption spectroscopy (XAS) for investigations of electronic structure at soft x-ray energies. At sufficiently low momentum transfer (q), NIXS probes the same final states as XAS; however, NIXS does so while using hard incident x-rays, ensuring bulk-sensitivity of measurements. At higher q, NIXS is sensitive to higher-order multipole transitions, providing information regarding final-state symmetries that is inaccessible by soft x-ray techniques. This q-dependence is exploited in a study of Na 1s core excitons in NaCl and NaF, important test cases for understanding final-state effects in insulators. The bulk-sensitivity of NIXS is utilized to study the controversial topic of charge compensation in lithium-ion battery cathodes during electrochemical cycling. Previous work on such materials has been restricted to spectroscopies that are prone to surface-sensitivity and, accordingly, are incompatible with additional experimental apparatus such as electrochemical cells. This also complicates the handling of air- and water-sensitive cathode materials. We present the first in situ, bulk-sensitive measurements of LixTiS2, the cathode material used in the first rechargeable lithium-ion batteries, and Li1– xCoO2, currently the most commonly-used commercial cathode material. |
