Observation of Iron Spin-States using Tabletop X-ray Emission Spectroscopy and Microcalorimeter Sensors

Published: December 02, 2015


Young Il Joe, Galen C. O'Neil, Luis Miaja Avila, Joseph W. Fowler, Kevin L. Silverman, Daniel S. Swetz, Joel N. Ullom, Ralph Jimenez


X-ray emission spectroscopy (XES) is a powerful probe of the electronic and chemical state of elemental species embedded within more complex compounds. X-ray sensors that combine high resolving power and high collecting efficiency are desirable for photon-starved XES experiments such as measurements of dilute, gaseous, and radiation-sensitive samples, time-resolved measurements, and in-laboratory XES where the exciting x-ray fluxes available are much less intense than at large facilities. To assess whether arrays of cryogenic microcalorimeters will be useful in photon- starved XES scenarios, we demonstrate that these emerging energy-dispersive sensors can detect the spin-state of two different iron compounds, Fe2O3 and FeS2, from the perturbing effect of the local 3d magnetic moment on the Kα and Kβ x-ray transitions. The measurements were conducted using a picosecond pulsed laser-driven plasma as the exciting x-ray source. The use of this tabletop source suggests that time-resolved in-laboratory XES will be possible in the future. We also present simulations of Kα and Kβ spectra that reveal the spin-state sensitivity of different combinations of sensor resolution and accumulated counts. These simulations predict that use of the Kα complex is attractive, that our current experimental apparatus can perform time-resolved XES measurements on some samples on timescales of a few 10s of hours per time delay, and that anticipated improvements in source and detector technology will enable in-laboratory, time-resolved XES on a broad range of samples on timescales near an hour.
Citation: Journal of Physics B-Atomic Molecular and Optical Physics
Volume: 49
Pub Type: Journals
Created December 02, 2015, Updated November 10, 2018