## 3 Results  
The IXS measurement of the C K-edge recorded from a chemical vapor deposition (CVD) diamond sample with the von Hamos spectrometer is plotted in Figure 3. The incident beam energy was set to 8350 eV. The spectrum is shifted in energy according to the energy conservation rule, in order to be compared with experimental data recorded by means of Electron Loss Near Edge Spectroscopy (ELNES) [33, 34]. As shown, excellent agreement is obtained between the spectra. A total incident photon flux of around 10\({}^{15}\)-10\({}^{16}\) photons was needed to record a good quality IXS signal. Following the ELNES and XAS experimental and theoretical interpretation, the first peak at around 292 eV corresponds to 1s\(\rightarrow\)\(\sigma\)* excitation, while the features from 295-310 eV relate to \(\sigma\)-type unoccupied states, and the peak at 328 eV is the first EXAFS feature.  
Figure 2: Elastically scattered X-rays measured using the von Hamos spectrometer with the Si(444) diffraction signal at a Bragg angle of around 80 degrees and an X-ray energy of 8030 eV. The incident beam was monochromatized using an Si(311) channel-cut monochromator, resulting in a 250 meV incident X-ray bandwidth. Inset: A Gaussian fit to the experimental measurement (red) overlaid with the de-convolved spectrometer energy resolution (blue).  
The IXS technique has the capability to probe not only K-edges of low \(Z\) elements but also the absorption spectra of higher electronic levels. As an example, we performed the IXS measurements on Ti to detect the 3p and 3s absorption spectra by means of IXS. As sample, we used a 5-\(\upmu\)m-thick Ti foil. The spectrometer settings were the same as in the case of the IXS C K-edge measurements with the incident beam energy tuned to energy of 8070 eV. The resulting spectrum is plotted in Figure 4. Two distinct features are observed at an energy transfer range between 20 and 80 eV. The first feature located at 30-45 eV corresponds to the 3p absorption spectrum. A sharp peak at 38 eV is detected that corresponds to 3p\(\rightarrow\)d excitation. The second feature at energies above 55 eV relates to 3s absorption. Resonance excitation is observed at 60 eV, that corresponds to dipole 3s\(\rightarrow\)p transition. Note that these transitions probe the same final electronic states as Ti K- and L-edge spectroscopies, and are difficult to address without using electron spectroscopic techniques.  
Figure 4: IXS signal of Ti foil showing the excitation signatures of 3p\(\rightarrow\)d and 3s\(\rightarrow\)p.  
Figure 3: IXS signal of the carbon K-edge of a chemical vapor deposition (CVD) diamond sample. Electron Loss Near Edge Spectroscopy (ELNES) data adapted from Reference [33] with permission from the Royal Society of Chemistry.  
One of the significant advantages of the IXS technique is the ability to probe bulk samples, such as liquid water. The oxygen IXS signals from water are shown in Figure 5. The O K-edge measurement (Figure 5 right) shows the characteristic XAS and EXAFS of liquid water [35; 36; 37], with no contribution from the gas-phase species [38], as expected for a bulk measurement. As for the Ti sample, the dispersive spectrometer can also easily access higher-lying excitations, in this case excitations from the 1b\({}_{2}\) and 2a\({}_{1}\) molecular orbitals of the water molecule [39]. In general, these types of excitations are measured using photoemission, which requires vacuum techniques to be applied [40]. Here, we measure the signals from the bulk liquid under ambient atmospheric conditions.