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1.
Monitoring of the particles above the unpaved road by lidar technique
Urška Koren, William Eichinger, 2011, original scientific article

Abstract: Basic concepts of laser-based technique LIDAR (LIght Detection and Ranging) are discussed in this article as well as advantages and disadvantages. Presented are measurements of relative particulate concentrations above an unpaved road which were performed in a rural area near the Iowa City, Iowa, USA. The LIDAR system used in these measurements is a small, scanning LIDAR that uses elastic backscattering to obtain information on the amount of atmospheric aerosols. In the elastic LIDAR, light scattered back towards the LIDAR system from molecules and particles in the atmosphere is collected by a telescope and is detected with a photodiode. A Big Sky Laser model CFR-200 Nd:YAG laser operating at 1.064 microns is used to generate the LIDAR's outgoing signal. The laser is attached directly to the top of a 26 cm, f/10 Cassegrian telescope. A series of pulses are summed to make a single scan. A series of scans is used to build up a two- dimensional map of relative atmospheric aerosol concentrations. With a maximum range of about 6-8 km, a range resolution of 2.5 m, and a time resolution of 30 s, the LIDAR is capable of very detailed mapping of aerosols.
Keywords: LIDAR technique, particulate concentration, traffic emissions
Published in RUNG: 12.07.2023; Views: 621; Downloads: 2
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Effect of duty cycle on photothermal phenomenon – a thermal lens study
Mohanachandran Nair Sindhu Swapna, 2019, original scientific article

Keywords: Photothermal phenomena Thermal lens technique Optical chopper Duty cycle variation
Published in RUNG: 05.07.2022; Views: 1019; Downloads: 0
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Chemical (in)stability of interfaces between different metals and Bi[sub]2Se[sub]3 topological insulator
Katja Ferfolja, Mattia Fanetti, Sandra Gardonio, Matjaž Valant, 2018, published scientific conference contribution abstract

Abstract: In recent years a classification of materials based on their topological order gained popularity due to the discovery of materials with special topological character – topological insulators (TI). TI have different band structure than regular insulators or conductors. They are characterized by a band gap in the bulk of the material, but at the surface they possess conductive topological surface states (TSS) that cross the Fermi level. TSS are a consequence of the non-trivial bulk band structure and have properties that differ from ordinary surface states. They are robust toward contamination and deformation of the surface. Additionally, they are also spin polarized, which means that an electron spin is locked to a crystal momentum and, therefore, backscattering during transport is suppressed [1]. Due to their specific properties the TI could be used in fields of spintronics, quantum computing and catalysis [2]. The investigation of the interfaces between metals and the TI has not been given much attention even though its characterization is interesting from fundamental physics and applicative point of view. (In)stability of the contacts with metal electrodes, in a form of a chemical reaction or diffusion, has to be taken into account since it can affect the transport properties of the material or increase the contact resistance. Our research is dedicated to the study of the metal/TI interfaces, in particular to Bi2Se3 with deposited metals that are relevant for electrical contacts (Au, Ag, Pt, Cr, Ti). The thermal and chemical stability of the interfaces are of fundamental importance for understanding the contact behavior, therefore, we focused our work to the characterization of these properties. The metal/TI interfaces are investigated mainly with an electron microscopy (SEM, TEM, STM), EDX microanalysis and XRD. Our previous studies showed that the interface between Bi2Se3, and Ag deposited either chemically or from a vapor phase, results in the formation of new phases already at room temperature [3]. On the contrary, Au deposited on the Bi2Se3 surface shows very limited reactivity and is stable at RT, but diffusion and coalescence of the metal are observed starting from 100 °C [4]. In this contribution, we will present further characterization on the evolution of the Ag/Bi2Se3 and Au/Bi2Se3 interfaces, show preliminary results about recently investigated systems (Pt/Bi2Se3, Ti/Bi2Se3) and compare the thermal and chemical stability of the systems under investigation.
Keywords: thermal lens spectrometry, photothermal beam deflection spectroscopy, dye remediation, photothermal technique, photocatalytic degradation, reactive blue 19, TiO2 modification
Published in RUNG: 20.08.2021; Views: 2156; Downloads: 0
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Determination of Dissolved Iron Redox Species in Freshwater Sediment using DGT Technique Coupled to BDS
Hanna Budasheva, Aleksander Kravos, Dorota Korte, Arne Bratkič, Yue Gao, Mladen Franko, 2019, original scientific article

Abstract: In this work we have developed a novel method for determination of iron redox species by the use of diffusive gradients in thin-film (DGT) technique coupled to photothermal beam deflection spectroscopy (BDS). The combination of both methods achieved low limit of detection (LOD) of 0.14 μM for Fe (II) ions. The total Fe concentration determined in the Vrtojbica river sediment (Slovenia, Rožna Dolina, 5000 Nova Gorica) was 49.3 μgL–1. The Fe (II) and Fe (III) concentra- tion amounted to 12.8 μgL–1 and 39.9 μgL–1, respectively. Such an approach opens new opportunities for monitoring the content of iron species in natural waters and sediments and provides highly sensitive chemical analysis and an accurate qualitative and quantitative characteristic of the materials under study.
Keywords: Beam deflection spectroscopy, diffusive gradients in thin-film technique, iron redox species, photothermal techniques, sediment
Published in RUNG: 26.02.2019; Views: 3610; Downloads: 114
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