For example, soft X-ray studies may be surface sensitive and they require a vacuum environment.
This makes studies of many substances, such as numerous liquids impossible using soft X-ray absorption.
In his report of finding of a new type of scattering, Sir Chandrasekhara Venkata Raman proposed that a similar effect should be found also in the X-ray regime.
Around the same time, Bergen Davis and Dana Mitchell reported in 1928 on the fine-structure of the scattered radiation from graphite and noted that they had lines that seemed to be in agreement with carbon K shell energy.
It was soon realized that the XRS peak in solids was broadened by the solid-state effects and it appeared as a band, with a shape similar to that of a XAS spectrum.
This is due to the very small XRS probability of the incident photons, requiring radiation with a very high intensity.
XRS belongs to the class of non-resonant inelastic X-ray scattering, which has a cross section of Here,
It was shown by Yukio Mizuno and Yoshihiro Ohmura in 1967 that at small momentum transfers
the XRS contribution of the dynamic structure factor is proportional to the X-ray absorption spectrum.