Soft X-Ray SHG from graphite

We observed an SHG signal at the carbon K-edge! 



Lam et al., Phys. Rev. Lett. 120, 023901 (2018)

We report the observation of soft X-ray second harmonic generation near the carbon K-edge (~284 eV) in graphite thin films generated by high intensity, coherent soft x-ray pulses at the FERMI free electron laser. Our experimental results and accompanying first-principles theoretical analysis highlight the effect of resonant enhancement above the carbon K edge and show the technique to be interfacially sensitive in a centrosymmetric sample with second harmonic intensity arising primarily from the first atomic layer at the open surface. This technique and the associated theoretical framework demonstrate the ability to selectively probe interfaces, including those that are buried, with elemental specificity, providing a new tool for a range of scientific problems.

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Ultima modifica il Mercoledì, 19 Maggio 2021 18:51