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Keywords: cellulose, camphor soot, lignin, PVDF, photothermal, beam deflection, hydroxyl groups
Published in RUNG: 21.08.2023; Views: 340; Downloads: 4
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Keywords: organic bulk-heterojunction solar cells, polymer-fullerene solar cells, photothermal beam deflection spectrometry, non-radiative recombination, thermal diffusivity, frequency domain methods
Published in RUNG: 09.01.2023; Views: 925; Downloads: 16
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Abstract: The present work proposes a method of downscaling the thermal diffusivity (α) of MoO3 thin films through annealing temperature-induced nano-lamelle formation. The thermal diffusivity modification of the MoO3 films, prepared by the doctor blade method, is investigated by the sensitive transverse photothermal beam deflection technique. The X-ray diffraction analysis confirms the structural phase transformation from monoclinic to orthorhombic in the films annealed from 300 to 450 °C. The thermal induced anisotropy of the film is evident from the variation of the morphology index and texture coefficient. The field emission scanning electron microscopic analysis unveils the morphology modifications from blocks to the nano-lamelle structure with layers of average thickness ~ 77 nm. The thermal diffusivity measurement reveals a 53% reduction upon annealing the film to 450 °C. The drastic reduction is achieved through the annealing temperature-induced nano-lamelle formation and the phase transformation from monoclinic to orthorhombic in the MoO3 films.
Keywords: thermal diffusivity, molybdenum oxide, thin film, nano-lamelle, photothermal beam deflection
Published in RUNG: 04.07.2022; Views: 816; Downloads: 24
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Keywords: thermal properties, Photothermal radiometry, beam deflection spectrometry, thermal lens spectrometry, thermoreflectance
Published in RUNG: 30.06.2022; Views: 916; Downloads: 36
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Abstract: Sea-ice borne iron has been found to be an important factor controlling Southern Ocean phytoplankton growth [1]. Knowing the amount and chemical speciation of its labile fraction in sea ice would advance our understanding of the involved processes. Unfortunately, it is rather difficult to perform their measurement because of limited access to the Antarctic. Thus there is a strong need for the development of a quick, simple and reliable technique for determination of iron and its speciation in sea-ice that ensures also low enough limits of detection. Recently, diffusive gradients in thin films (DGT) have been widely used as passive samplers for collecting time-averaged data on the concentrations of transition metals in different media [2]. DGTs are further coupled to an analytical technique that in case of detecting metals in passive sampler films primarily requires their extraction [3], which may potentially lead to changes of the metal specification. In the present study, the beam deflection spectrometry (BDS) is coupled to DGT and used to determine the average concentration of iron in the sea ice samples collected at the Davis Station in the Antarctic. Such a combined technique has been already successfully applied for detecting labile iron species in freshwater sediments [4]. The obtained BDS data were validated by thermal lens spectrometry (TLS) and UV-Vis spectrophotometry (SPEC). The distribution of iron species over a given ice surface area using the DGT-BDS technique revealed total iron concentrations in the range of 0.6 – 5.3 μgL-1, whereas the Fe2+ content was found to be in the range of 0.1 – 1.5 μgL-1. The range taking into account all of the measurement points (5×4), the precision of a single measured point is 0.2 μgL-1. The calculated 24 h-average concentration of total Fe labile species in the ice by using BDS is 2.3 ± 0.5 μgL-1, which coincides with data obtained by SPEC (2.5 ± 0.4 μgL-1) and TLS (2.39 ± 0.02 μgL-1). Our results indicate that it is possible to develop a robust, contamination-resilient detection method for measuring the labile iron species concentration in the sea ice. In opposite to TLS and SPEC, BDS-DGT provides reliable information not only about the speciation of iron but also about their distribution on the ice surface.
Keywords: beam deflection spectrometry, diffusive gradients, thin films, iron species, photothermal techniques, Antarctic sea ice
Published in RUNG: 30.11.2021; Views: 1806; Downloads: 0
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