The photons transmitted through the sample are measured conventionally using a point detector such as a photomultiplier tube. The principle of operation of this instrument can be found in literature . In short, STXM is based on the fundamentals of XAS. Absorption of an X-ray photon creates an excited state where a core electron fills an empty orbital. Since the binding energies of core electrons is a characteristic of each element, this technique is element sensitive . However, this is not all, since the spatial distribution of empty electronic levels or orbitals is also related to the molecular bonding, spectroscopy near the X-ray absorption edge is also sensitive to chemical moieties. Exploring this edge through spectroscopy is called NEXAFS (near edge X-ray absorption fine structure) or XANES (X-ray absorption near edge structure) spectroscopy. These chemical moieties often have distinct features corresponding to specific known energies . A thin film composed of materials consisting of different chemical functionalities, if raster scanned (imaged) at different energies, will offer image contrast at these energies enabling chemical compositional mapping (or molecular orientation mapping ) of the sample.