Confocal micro-X-ray fluorescence spectroscopy with a liquid metal jet source†
To further widen the applicability of confocal micro-X-ray fluorescence spectroscopy (CMXRF) a novel setup using a liquid metal jet source as excitation was build up and characterized. We present a comparison concerning lateral, depth resolution and performance with state-of-the-art spectrometers using microfocus X-ray tubes. The efficiency of this setup scales with the used power, resulting in a >8-fold intensity increase in the excitation radiation, or measurement time decrease compared to low power X-ray tubes. The adaptation of the excitation lens' transmission to the energy of the characteristic lines additionally increases the sensitivity of the setup, yielding for selected elements an intensity gain of up to a factor of 60. As an application example, a 3D map of a millet seed is evaluated with an uncertainty estimation for incomplete pathway information. With the presented superior performance, full 3D elemental mapping in the laboratory is rendered feasible for classes of samples with low fluorescence intensities such as biological specimen.