• Kern, Jan
• Rohringer, Nina
• Kroll, Thomas
• Weninger, Clemens
• Boutet, Sébastien
• Pastor, Ernest
• Mercadier, Laurent
• Decker, Franz-Josef
• Majety, Vinay P.
• Koralek, Jake
• Yano, Junko
• Zhu, Diling
• Fransson, Thomas
• Marinelli, Agostino
• Sokaras, Dimosthenis
• Guetg, Marc W.
• Koglin, Jason
• Bergmann, Uwe
• Aquila, Andy
• Yachandra, Vittal K.
• Deponte, Daniel P.
• Fuller, Franklin D.
• Zhang, Yu
• Lutman, Alberto
• Alonso-Mori, Roberto

Abstract

We report the observation and analysis of the gain curve of amplified Kα x-ray emission from solutions of Mn(II) and Mn(VII) complexes using an x-ray free electron laser to create the 1s core-hole population inversion. We find spectra at amplification levels extending over 4 orders of magnitude until saturation. We observe bandwidths below the Mn 1s core-hole lifetime broadening in the onset of the stimulated emission. In the exponential amplification regime the resolution corrected spectral width of ∼1.7  eV FWHM is constant over 3 orders of magnitude, pointing to the buildup of transform limited pulses of ∼1  fs duration. Driving the amplification into saturation leads to broadening and a shift of the line. Importantly, the chemical sensitivity of the stimulated x-ray emission to the Mn oxidation state is preserved at power densities of ∼10^{20}  W/cm^{2} for the incoming x-ray pulses. Differences in signal sensitivity and spectral information compared to conventional (spontaneous) x-ray emission spectroscopy are discussed. Our findings build a baseline for nonlinear x-ray spectroscopy for a wide range of transition metal complexes in inorganic chemistry, catalysis, and materials science.

Topics

• impedance spectroscopy
• X-ray emission spectroscopy