This paper reviews non-resonant meV-resolved inelastic x-ray scattering (IXS) as a complementary method to inelastic neutron scattering (INS). Two aspects of IXS that are notable in this context are (1) that x-rays allow straightforward measurements of phonons in small (sub-mm, and even ~0.01 mm) samples with ~1 meV resolution and excellent Q resolution and (2) that x-rays avoid the kinematic constraints of INS. The first allows both new geometries (thin films, diamond anvil cells) and easy access to new materials, while the second allows high-quality data on disordered materials – e.g. scans with sub-meV resolution to arbitrarily high energy transfer are possible, even at Q = 1nm^-1. The review briefly discusses the spectrometers and compares the practical forms for the dynamic structure factor, 𝑆(𝑄, 𝜔), for crystals, glasses and liquids. This is followed by a longer review of work on liquids and then shorter discussion of work on glasses, crystals, and in specific geometries. The paper is designed to be complementary to a longer introduction/review of IXS at http://arxiv.org/abs/1504.01098 .

Recent development in the resonant inelastic x-ray scattering (RIXS) instrumentation has enabled systematic investigations into the collective magnetic excitations in quantum materials. In this article, we introduce RIXS studies of the magnetic excitation spectra of two ruthenium oxides, which are difficult to access by neutron spectroscopy. We discuss how the complementary use of RIXS and inelastic neutron scattering provides an in-depth understanding of magnetic excitations in solids.