An imaging method based on scanning a sample with a focused beam of soft X-rays and measuring the intensity of radiation transmitted through successive points of the material. This process yields a microscopic image of the sample. Owing to high spatial resolution (20 nm – 100 nm) and the ability to select the wavelength (i.e. radiation energy), it is possible to obtain images containing information about the chemical composition and electronic state of the analysed areas. Additionally, the possibility of using variable photon polarisation enables the imaging of magnetic domains.

The STXM technique allows for:

• mapping the distribution of elements and their chemical bonds (e.g. differentiation of oxidation states),
• analysing structure and composition at the micro- and nanoscale,
• imaging magnetic domains.

STXM is a volume imaging technique – it provides information from within the sample, not just from its surface. However, the samples must be very thin, with a maximum thickness of a few micrometres. They are typically deposited directly onto thin Si₃N₄ membranes or prepared as thin slices using microtomy or FIB (Focused Ion Beam) techniques.

Although the use of soft X-rays requires vacuum conditions, STXM enables imaging of samples in a gaseous environment: He, Ar, O₂, N₂, CO₂, and across a pressure range from vacuum to atmospheric pressure. This makes it possible to simulate real-world conditions for the sample under investigation.

STXM finds applications in fields such as:

• Materials engineering (characterisation of multilayer structures, material degradation and ageing),
• Electrochemistry and energy (analysis of electrode materials in cells and batteries, charge/discharge cycles),
• Life sciences and biomaterials (imaging of cells, tissues, biofilms, including under near-natural conditions),
• Environmental science (analysis of atmospheric samples, soil and sediment pollutants).

The STXM method is available at the DEMETER beamline, operating in the energy range of 100–2000 eV.