Creating double core hole two sites in N$_2$ molecules using the Linac Coherent Light Source

We have measured double core hole two sites in N$_2$ molecules using the intense short x-ray laser pulses from the Linac Coherent Light Source free electron laser. This is achieved within the time scale of the single-core-hole state lifetime via sequential core ionization. This work extends previous work [1, 2] and demonstrates that both photoelectron and Auger spectroscopy allow the measurement of double core hole two sites. The latter are very sensitive to the chemical environment and present a new chemical analysis tool. This work was supported in part by the DOE-SC-BES, Chemical Sciences, Geosciences and Biosciences Division. [1] L.~Fang \textit{et al.}, Phys. Rev. Lett. \textbf{105}, 083005 (2010). [2] J.~Cryan \textit{et al.}, Phys. Rev. Lett. \textbf{105}, 083004 (2010).