EPAC will be capable of performing X-ray absorption spectroscopy (XAS) techniques including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). EPAC will be able to produce X-rays across a wide energy range allowing techniques using both hard and soft X-rays on the same beamline with minor changes in the interaction configuration.
X-ray absorption spectroscopy (XAS) is a category of spectroscopic techniques where a sample is exposed to X-rays and a spectrum is measured.
Techniques include X-ray absorption near edge structure (XANES) spectroscopy (also known as NEXAFS or near edge X-ray absorption fine structure)and extended X-ray absorption fine structure (EXAFS). XANES and EXAFS are extremely powerful techniques with applications in a wide range of areas including chemistry, electronics, surface science, mineralogy and biological sciences.
When exposed to X-rays, materials have a spectral region where absorption changes rapidly over a few eV, referred to as an edge (L or K). At energies just above the edge, there is a fingerprint of absorption (analysed in XANES) and at energies above that, there is the fine structure region (analysed in EXAFS). These fingerprints are unique to each chemical element, allowing quantitative trace analysis.
Notably, proof of concept work for laser-driven XANES has been performed at the CLF. EPAC will be able to produce a high X-ray flux at 10Hz repetition rate, facilitating further development of laser-driven XAS.
EPAC will be able to produce X-rays across a wide energy range allowing techniques using both hard and soft X-rays on the same beamline with only minor changes in the laser target areas. Furthermore, the pulse duration of laser-driven X-rays is in the order of a few femtoseconds, thus allowing it to be synchronised to other laser pulses giving the capability for femtosecond scale pump-probe experiments.