Near-edge x-ray absorption fine structure spectroscopy with laser plasma sources of soft x-ray radiation

Abstract

Acquiring spectral information about the samples using near edge X-ray absorption fine structure (NEXAFS), which is a well-known and established method employed for compositional analysis of the samples, yields information about its elemental composition through the observation of the spectral features in the vicinity of the high energy side of the X-ray absorption edge. In particular, NEXAFS is often used to study the structure of intermolecular bonds of polymers by probing the electronic transitions from the core level to the unoccupied states. The NEXAFS spectra contain information which is element specific, indicating additionally the structure of the molecular bonds. This requires short wavelength sources, capable of delivering sufficient flux to achieve high signal-to-noise and of high quality spectral data in the time frame from fs to ns. These sources are synchrotrons, and FEL, but also compact sources, such as the laser-plasma source based on a double stream gas puff target. The applications of this source to recently developed compact NEXAFS spectroscopy system and an overview of some recent applications will be the main topic of this overview paper. Acquisition of static NEXAFS data for composition analysis of various materials and organic compounds, a raster scanning of the sample and acquiring spatially localized spectral data in so-called spectromicroscopy, as well as a single shot NEXAFS, allowing future timeresolved studies, will be presented with references to the original works.