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Experimental characterization of the structural, electronic and dynamic properties of dilute systems in aqueous solvents, such as nanoparticles, molecules and proteins, are nowadays an open challenge. X-ray absorption spectroscopy (XAS) is probably one of the most established approaches to this aim as it is element-specific. However, typical dilute systems of interest are often composed of light elements that require extreme-ultraviolet to soft X-ray photons. In this spectral regime, water and other solvents are rather opaque, thus demanding radical reduction of the solvent volume and removal of the liquid to minimize background absorption. Here, we present an experimental endstation designed to operate a liquid flat jet of sub-micrometre thickness in a vacuum environment compatible with extreme ultraviolet/soft XAS measurements in transmission geometry. The apparatus developed can be easily connected to synchrotron and free-electron-laser user-facility beamlines dedicated to XAS experiments. The conditions for stable generation and control of the liquid flat jet are analyzed and discussed. Preliminary soft XAS measurements on some test solutions are shown. [ABSTRACT FROM AUTHOR]

To optimize the catalytic functionality of cerium oxide it is important to understand the structural modifications associated with reduction and the role of the proximity of metals, which are often coupled with the oxide in the applications. For this purpose, the evolution of the short‐ and long‐range structure of cerium oxide ultrathin epitaxial films and nanostructures supported on Pt(111) is investigated using X‐ray absorption spectroscopy at the Ce L3 edge and surface X‐ray diffraction, during reduction by thermal treatments in vacuum. In epitaxial nanoislands reduction is associated with a contraction of the Ce–O distance and with the appearance of CePt bonds. The formation of a phase with a (2 × 2) periodicity after a thermal treatment at 1023 K is ascribed to the formation of a Pt5Ce alloy. Films of 3 nm thickness do not show, on average, significant structural modifications with the same thermal treatment, consistent with the hypothesis that the reduction involves only the topmost surface layers and it does not influence significantly the bulk structure of the material. This study demonstrates a strong interaction between cerium oxide and platinum, which has implications for the reactivity and stability of catalysts based on metals combined with reducible oxides. [ABSTRACT FROM AUTHOR]

Absorbing near‐infrared (NIR) photons, with longer wavelengths, in atomically thin monolayer MoS2 presents a significant challenge due to its weak optical absorption and narrow absorption bands. Consequently, MoS2‐based photodetector devices often experience low responsivity and a limited detection window. Herein, a novel InAs@ZnSe core@shell/1L‐MoS2 heterostructure, leveraging InAs@ZnSe as the primary infrared‐absorbing material and exploiting the formation of a type‐II heterostructure is showcased. Steady‐state and time‐resolved spectroscopy, along with optoelectronic characterization, are employed to investigate photo‐induced charge transfer dynamics. The results show efficient hole transfer to InAs@ZnSe upon excitation of both materials. Instead, with selective excitation of InAs@ZnSe, electron transfer is observed from InAs@ZnSe to the 1L‐MoS2. The heterostructure demonstrates a broadband photoresponse spanning the wavelength range of 300 to 850 nm, exhibiting a Responsivity of ≈103 A/W and Detectivity of ≈1011 Jones. The signal‐to‐noise ratio substantially increases by 3 to 4 orders of magnitude for 700 and 850 nm excitation compared to pristine 1L‐MoS2. The enhancement in photoresponse and signal‐to‐noise ratio is attributed to increased absorption, which helps eliminate defect and trap states, thereby promoting the photogating effect. [ABSTRACT FROM AUTHOR]