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1.
Application of complex geometrical optics to determination of thermal, transport, and optical parameters of thin films by the photothermal beam deflection technique
Dorota Korte, Mladen Franko, 2015, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ... spectrometry, photothermal beam, geometrical optics, thin films, ...
Ključne besede: spectrometry, photothermal beam, geometrical optics, thin films
Objavljeno: 16.06.2016; Ogledov: 3617; Prenosov: 122
URL Polno besedilo (0,00 KB)

2.
Trace Detection and Photothermal Spectral Characterization by a Tuneable Thermal Lens Spectrometer with White-Light Excitation
Mladen Franko, Dorota Korte, Humberto Cabrera, 2018, izvirni znanstveni članek

Opis: In the thermal lens experimental set-up we replaced the commonly employed pump laser by a halogen lamp, combined with an interference lter, providing a tuneable, nearly monochromatic pump source over the range of wavelengths 430–710 nm. Counter-propagating pump and probe beams are used and a 1 mm path-length sam- ple cell together with the interference lter makes an optical cavity, providing ampli cation of the thermal lens signal, which leads to enhancement of the measurement sensitivity, and enables detection of absorbances on the order of 5×10− 6. Ampli ed thermal lens signal allows us to replace the typical lock-in ampli er and digital os- cilloscope with a silicon photodetector, Arduino board, and a personal computer, offering the possibility for a compact, robust and portable device, useful for in- eld absorption measurements in low concentration or weakly absorbing species. The use of a white light source for optical pumping, an interference lter for wavelength selection and direct diagnostic of the thermal lens signal increase the versatility of the instrument and simpli- es substantially the experimental setup. Determination of Fe(II) concentrations at parts per billion levels was performed by the described white-light thermal lens spectrophotometer and the absorption spectrum for 50μg/ L Fe(II)-1,10-phenanthroline was well reproduced with an average measurement precision of 4%. The obtained limits of detection and quantitation of Fe(II) determination at 510nm are 3μgL− 1 and 11μgL− 1, respectively. The calibration curve was linear in the concentration range of LOQ-500μgL− 1 with reproducibility between 2% and 6%, con rming that this instrument provides good spectrometric capabilities such as high sensitivity, tune- ability and good reproducibility. In addition, the versatility of the instrument was demonstrated by recording the photothermal spectrum of gold nanostructured material and determination of excitation wavelength with most ef cient optical to thermal energy conversion, which differs considerably (cca 100 nm) from the absorption maximum of the investigated sample.
Najdeno v: ključnih besedah
Povzetek najdenega: ...thermal lens spectrometry, Fe(II) determination, photothermal technique, multi-wavelength excitation...
Ključne besede: thermal lens spectrometry, Fe(II) determination, photothermal technique, multi-wavelength excitation
Objavljeno: 21.02.2018; Ogledov: 2867; Prenosov: 0
.pdf Polno besedilo (889,82 KB)

3.
Photocatalytic properties of metal modified TiO2 by photothermal techniques
Mladen Franko, Dorota Korte, Urška Lavrenčič Štangar, Olena Pliekhova, Humberto Cabrera, Zeinab Ebrahimpour, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: ključnih besedah
Povzetek najdenega: ...Thermal lens spectrometry, Photothermal beam deflection spectroscopy, Dye remediation, Photothermal...
Ključne besede: Thermal lens spectrometry, Photothermal beam deflection spectroscopy, Dye remediation, Photothermal technique, Photocatalytic degradation, Reactive Blue 19, TiO2 modification
Objavljeno: 09.11.2018; Ogledov: 2423; Prenosov: 0
.pdf Polno besedilo (208,76 KB)

4.
A multi-thermal-lens approach to evaluation of multi-pass probe beam configuration in thermal lens spectrometry
Humberto Cabrera, Leja Goljat, Dorota Korte, Ernesto Marin, Mladen Franko, izvirni znanstveni članek

Opis: In this work, a recently proposed thermal lens instrument based on multi-pass probe beam concept is investigated and described as a multi-thermal-lens equivalent system. A simulation of the photothermal lens signal formation in a multi-thermal-lens equivalent configuration of the system is performed and validated by comparing the experimental signals of single, dual and ten-pass configurations to theoretically calculated values. The theoretically predicted enhancement of the signal is 9 to 10-fold for a weak thermal lens when comparing the ten-pass configuration with the conventional single-pass thermal lens system. Experimentally achieved signal enhancement in the ten-pass system is 8.3 for pure ethanol sample and between 8 and 9 for solutions with different concentrations of the Fe(II) - 1,10-Phenanthroline complex. Additionally, a value of 9.1 was calculated as the ratio of the slopes of the calibration lines obtained using the ten-pass and single-pass configurations. The achieved limit of detection for determination of Fe(II), in the ten-pass configuration, was 0.4 µgL-1, with a relative standard deviation around 4.5%, which compares favorably with previously reported results for TLS determination of Fe(II) in thin samples using low excitation power. For the multi-pass configuration the linear range of measurement is reduced when compared to the single-pass configuration. This is explained by the theoretical analysis of the photothermal signal under multi-pass condition, which shows the important contribution of the nonlinear term in the theoretical expression for the photothermal signal. The ten-pass configuration, which is presented and validated experimentally for the first time, offers important signal enhancement needed in recently developed TLS instruments with tunable, low power excitation sources.
Najdeno v: ključnih besedah
Povzetek najdenega: ...multi-thermal-lens equivalent system. A simulation of the photothermal lens signal formation in a multi-thermal-lens equivalent...
Ključne besede: Thermal lens spectrometry, Photothermal detection, Trace determination, Chemical sensor
Objavljeno: 10.12.2019; Ogledov: 2034; Prenosov: 0
.pdf Polno besedilo (656,75 KB)

5.
Chemical (in)stability of interfaces between different metals and Bi[sub]2Se[sub]3 topological insulator
Sandra Gardonio, Matjaž Valant, Katja Ferfolja, Mattia Fanetti, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...thermal lens spectrometry, photothermal beam deflection spectroscopy, dye remediation, photothermal technique,...
Ključne besede: thermal lens spectrometry, photothermal beam deflection spectroscopy, dye remediation, photothermal technique, photocatalytic degradation, reactive blue 19, TiO2 modification
Objavljeno: 20.08.2021; Ogledov: 961; Prenosov: 0
.pdf Polno besedilo (100,42 KB)

6.
Thermo-optical characterization of Cu- and Zr-modified TiO[sub]2 photocatalysts by beam deflection spectrometry
Mladen Franko, Dorota Korte, Humberto Cabrera, Olena Pliekhova, Zeinab Ebrahimpour, Urška Lavrenčič Štangar, Mahmoud Abdelhamid, 2021, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...photocatalysts, TiO2, Cu/Zr, photodegradation, material characterization, photothermal spectrometry...
Ključne besede: photocatalysts, TiO2, Cu/Zr, photodegradation, material characterization, photothermal spectrometry
Objavljeno: 23.11.2021; Ogledov: 652; Prenosov: 40
URL Polno besedilo (0,00 KB)
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Towards a novel method for iron species determination in Antarctic sea ice
Hanna Budasheva, Arne Bratkič, Dorota Korte, Mladen Franko, 2021, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...spectrometry, diffusive gradients, thin films, iron species, photothermal techniques, Antarctic sea ice...
Ključne besede: beam deflection spectrometry, diffusive gradients, thin films, iron species, photothermal techniques, Antarctic sea ice
Objavljeno: 30.11.2021; Ogledov: 687; Prenosov: 0
.pdf Polno besedilo (216,61 KB)
Gradivo ima več datotek! Več...

9.
Through-plane and in-plane thermal diffusivity determination of graphene nanoplatelets by photothermal beam deflection spectrometry
Stefano Bellucci, Hanna Budasheva, Behnaz Abbasgholi N. Asbaghi, Humberto Cabrera, Dorota Korte, 2021, izvirni znanstveni članek

Opis: In this work, in-plane and through-plane thermal diffusivities and conductivities of a freestanding sheet of graphene nanoplatelets are determined using photothermal beam deflection spectrometry. Two experimental methods were employed in order to observe the effect of load pressures on the thermal diffusivity and conductivity of the materials. The in-plane thermal diffusivity was determined by the use of a slope method supported by a new theoretical model, whereas the through-plane thermal diffusivity was determined by a frequency scan method in which the obtained data were processed with a specifically developed least-squares data processing algorithm. On the basis of the determined values, the in-plane and through-plane thermal conductivities and their dependences on the values of thermal diffusivity were found. The results show a significant difference in the character of thermal parameter dependence between the two methods. In the case of the in-plane configuration of the experimental setup, the thermal conductivity decreases with the increase in thermal diffusivity, whereas with the through-plane variant, the thermal conductivity increases with an increase in thermal diffusivity for the whole range of the loading pressure used. This behavior is due to the dependence of heat propagation on changes introduced in the graphene nano-platelets structure by compression.
Najdeno v: ključnih besedah
Ključne besede: graphene nanoplatelets, thermal diffusivity, thermal conductivity, photothermal spectrometry
Objavljeno: 30.11.2021; Ogledov: 596; Prenosov: 25
URL Polno besedilo (0,00 KB)
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10.
Investigations of the Thermal Parameters of Hybrid Sol–Gel Coatings Using Nondestructive Photothermal Techniques
Łukasz Chrobak, Dorota Korte, Hanna Budasheva, Miroslaw Maliński, Peter Rodič, Ingrid Milošev, Sylwia Janta-Lipińska, 2022, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...non-destructive testing, photothermal radiometry, photothermal beam deflection spectrometry, thermal diffusivity, thermal conductivity...
Ključne besede: hybrid sol–gel coatings, non-destructive testing, photothermal radiometry, photothermal beam deflection spectrometry, thermal diffusivity, thermal conductivity
Objavljeno: 03.06.2022; Ogledov: 179; Prenosov: 5
.pdf Polno besedilo (1,36 MB)

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