We report on subwavelength plasmon-polariton guiding by triangular metal wedges at telecom wavelengths. A high-quality fabrication procedure for making gold wedge waveguides, which is also mass-production compatible offering large-scale parallel fabrication of plasmonic components, is developed. Using scanning near-field optical imaging at the wavelengths in the range of 1.43-1.52 microm, we demonstrate low-loss (propagation length approximately 120 microm) and well-confined (mode width congruent with 1.3 microm) wedge plasmon-polariton guiding along triangular 6-microm-high and 70.5 degree-angle gold wedges. Experimental observations are consistent with numerical simulations performed with the multiple multipole and finite difference time domain methods.

ICP-MS is becoming a competitive technique for the measurement of plutonium isotopes. However, the abundance sensitivity (tailing of 238 U to m/z=239 and 240), isobaric and polyatomic ions interferences (e.g. U H +) are the most critical challenges for determination of low-level plutonium in high uranium samples. This work presents a new method to solve this problem using ICP-MS with two tandem quadrupole separators and dynamic collision/reaction cell combined with chemical separation. The interference of uranium hydrides (238 U 1 H + and 238 U 1 H2 +) was effectively eliminated using CO2 as reaction gas by converting hydrides to oxides of uranium ions (UO + /UO2 +), but still keep the intensity of Pu + signal. The tailing interference of 238 U + (abundance sensitivity) was intensively eliminated by significantly suppressing the 238 U + signal using CO2 as reaction gas and using two tandem quadrupole mass separators in the ICP-MS/MS. With these approaches, the overall interference of uranium was reduced to <110-8 , which is 3 orders of magnitude better than the conventional ICP-MS. Combined with chemical separation with a decontamination factor of 10 5 for uranium, an overall factor of 10 12 for elimination of uranium interference was achieved. The developed method was demonstrated to enable accurate determination of <10-15 g/g level plutonium isotopes in environmental samples even in uranium debris sample with a U/Pu atomic ratio up to 10 12. The developed method was validated by the analysis of spiked solution and certified reference materials of soil.

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Solar cells based on the wide band-gap Cu 2 BaSnS 4 (CBTS) photoabsorber have achieved open circuit voltages up to 1.1 V over a short development period, making CBTS an attractive material for tandem photovoltaic and photoelectrochemical cells. In this work, we explore an alternative CBTS growth route based on oxide precursors, and we propose TaS 2 as an alternative back contact material to the commonly used Mo/MoS 2 . The oxide precursor route does not require higher sulfurization temperatures than other more common fabrication routes, and it yields CBTS lms with negligible Stokes shift between photoluminescence maximum and band gap energy, while at the same time avoiding sulfur contamination of vacuum systems. The high work-function metallic TaS 2 compound is selected as a prospective hole-selective contact, which could also prevent the losses associated with carrier transport across the semiconducting MoS 2 layer. By comparing CBTS solar cells with Mo and TaS 2 back contacts, the latter shows 1 Page 1 of 29 ACS Paragon Plus Environment ACS Applied Energy Materials a signicantly lower series resistance, resulting in a 10% relative eciency improvement.Finally, we fabricate a proof-of-concept monolithic CBTS/Si tandem cell using a thin Ti(O,N) interlayer intended both as a diusion barrier and as a recombination layer between the two subcells.

The sulde perovskite LaYS 3 has been recently identied as a promising wide band gap photoabsorber material by computational screening techniques. In this study, we combine experiment and theory to comprehensively characterize LaYS 3 thin lms produced by sulfurization of sputter-deposited precursors. An attractive feature of LaYS 3 is its optimal band gap (2.0 eV) for application as a wide-band gap photoabsorber in 1 tandem solar energy conversion devices. Promisingly, the LaYS 3 lms are photoconductive, with a grain size in excess of 1 µm and comparable recombination timescales to state-of-the-art hybrid halide perovskite absorbers. Although the fabrication of solar cells based on LaYS 3 absorbers is complicated by the high temperature necessary to grow the compound, complete solar cells could be produced in this work by growing LaYS 3 on refractory metal back contacts. These are the rst reported solar cells based on a sulde perovskite absorber. A major reason for their poor performance could be the highly localized trap states observed directly by photoluminescence imaging of LaYS 3 , which may also explain the surprisingly long carrier lifetimes and the low carrier mobility found in this material.