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When ultrasound waves travel through an inhomogeneous medium, they become degraded. Typically, this wavefront degradation is compensated for by applying an “active” signal processing approach using multi-element transducers. Recently, a twin-layer “passive” approach using a Twin-Layer Ultrasound Phase Interference Compensator (TL-UPIC) has been proposed which operates without multi-element transducers. In this Technical Note, we compare the ability of both the active and passive TL-UPIC approaches to compensate for ultrasound wave degradation through an intermediate medium at sub-transducer element spatial resolution. Experimental comparisons between the active and passive approaches were conducted where the effective feature size of the intermediate medium was varied relative to the size of the transducer array elements. We show that if the feature size of the intermediate medium is larger than the size of the transducer elements that both the active and passive approach show equally good results. However, as the apparent feature size is decreased, the active method can no longer provide sufficient compensation while the passive method continues to compensate for the wavefront degradation. [ABSTRACT FROM AUTHOR]

Crucial for the advancement of electrochemical materials science is understanding the lateral variations in the elemental and chemical state of constituents induced by electrochemical reactions at nanoscales. This requires in situ studies to provide observables that contribute to both modeling beyond the phenomenological level and transducing exactly the functionally relevant quantities A range of X-ray coherent diffraction imaging (CDI) approaches has recently been proposed for imaging beyond the diffraction limit with potentially dramatic improvements of time resolution with chemical sensitivity. In this paper we report a selection of ptychography results obtained in situ after successive steps of electrochemically driven growth, complemented with absorption and phase spectroscopy at high lateral resolution. We demonstrate the onset of morphological instability feature formation and correlate the chemical state of Mn with local growth rate controlled by the current density distribution resulting from morphological evolution. [ABSTRACT FROM AUTHOR]

Diffraction peaks can lead to inaccurate elemental abundances in X-ray fluorescence maps. However, manually removing diffraction peaks is laborious while existing automated methods unnecessarily remove significant volumes of fluorescence data. Here we propose a new automated method to remove diffraction from multiple-detector spectra based on a statistical threshold. This method eliminates only the diffraction peaks from the spectra, retaining more of the fluorescence data and increasing the information content available for diffraction-free elemental quantification and mapping. By retaining the majority of the fluorescence data, the proposed method does not require an increase in dwell times or additional data to be collected to compensate for the removed fluorescence data. This method is therefore particularly valuable in instances where measurement time and data volumes are highly restricted, such as for instruments on planetary exploration missions like the Planetary Instrument for X-ray Lithochemistry on NASA's Mars 2020 mission Perseverance Rover. [Display omitted] • A statistical method is proposed to remove diffraction from XRF spectra. • The method can increase the spectral information content for quantification. • The method can increase the efficiency and lifetime of XRF instruments. [ABSTRACT FROM AUTHOR]