Double core-hole electron spectroscopy of formamide

The intense, femtosecond x-ray pulses generated at the Linac Coherent Light Source can produce double core-holes (DCH) by absorbing two photons sequentially prior to Auger decay [1,2]. DCH binding energies at different atomic sites are sensitive to the chemical environment and electron correlations. DCH features appear in photoelectron and Auger electron spectra. At the LCLS, we used 1000 - 1200 eV x-rays with estimated pulse durations $<$ 10 fs to record electron spectra of formamide, HCONH$_{2}$. The measured electron spectra are compared with calculated DCH binding energies at the C, O, and N sites of the molecule. [1] R. Santra \textit{et al.}, Phys. Rev. Lett. \textbf{103}, 013002 (2009). [2] L. Fang \textit{et al}., Phys. Rev. Lett. \textbf{105}, 083005 (2010).