XUV Fourier-Transform Spectroscopy

Absorption spectroscopy in the extreme ultraviolet (XUV) is scientifically extremely interesting as it gives insight into the electronic properties of the sample under investigation. High-resolution XUV absorption spectroscopy in particular can become a powerful tool to test and refine quantum mechanical models. Until now, however, it has mainly been confined to large-scale facilities. The goal of this project is implementing high-resolution XUV Spectroscopy at a table-top setup.
High harmonic generation (HHG) sources are very well suited for this purpose due to their high coherence and broad spectral coverage. Combining them with a highly stable Fourier-transform spectrometer promises to enable spectroscopy with simultaneously big bandwidth and high resolution.
A schematic of the spectrometer setup can be seen in the figure. Due to the lack of high-quality beam-splitting optics in the XUV, an interferometer in the infrared is used to split each pulse from an Ytterbium fiber amplifier system into two time-delayed pulses. They are used to drive the HHG source, which yields two XUV pulses of similar flux and adjustable time delay. These are absorbed by a sample before interfering on a photodiode. By scanning the time delay the interferogram is acquired, from the Fourier transform of which the spectral information can be determined.
This project strives to realize the table-top XUV absorption spectrometer with the highest spectral resolution to date, drastically improving accessibility of high-resolution XUV spectroscopy.