1. Accuracy of measurements of thermophysical parameters by dual-beam thermal-lens spectrometryVladislav R. Khabibullin, Mladen Franko, Mikhail A. Proskurnin, 2023, original scientific article Abstract: Thermal-lens spectrometry is a sensitive technique for determination of physicochemical
properties and thermophysical parameters of various materials including heterogeneous systems
and nanoparticles. In this paper, we consider the issues of the correctness (trueness) of measurements
of the characteristic time of the thermal-lens effect and, thus, of the thermal diffusivity determined
by dual-beam mode-mismatching thermal lensing. As sources of systematic errors, major factors—
radiation sources, sample-cell and detector parameters, and general measurement parameters—are
considered using several configurations of the thermal-lens setups, and their contributions are
quantified or estimated. Furthermore, with aqueous ferroin and Sudan I in ethanol as inert colorants,
the effects of the intermolecular distance of the absorbing substance on the correctness of finding the
thermophysical parameters are considered. The recommendations for checking the operation of the
thermal-lens setup to ensure the maximum accuracy are given. The results obtained help reducing
the impact of each investigated factor on the value of systematic error and correctly measure the
thermophysical parameters using thermal-lens spectrometry.
Keywords: thermal-lens spectrometry, accuracy, trueness, mode-mismatched schematic, measurements of thermal diffusivity
Published in RUNG: 20.01.2023; Views: 2316; Downloads: 16
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3. Hemichrome Determination by Thermal Lensing with Polyethylene Glycols for Signal Enhancement in Aqueous SolutionsViktoriya Galimova, Mladen Franko, Mikhail Proskurnin, Mingqiang Liu, 2018, original scientific article Abstract: The thermal lens technique is proposed for the determination of total hemoglobin in the form of reversible hemichrome. The conditions were optimized (concentration of sodium dodecyl sulfate, 2 mM) to attain the maximum sensitivity with the use of polyethylene glycols as signal enhancers. For polyethylene glycols with molecular weights 1500–35000 Da in a concentration range of 5–15% w/w (5–25 mM), the influence on thermal lens signal enhancement was estimated. It is shown that the use of 5% w/w polyethylene glycol 2000 provides the maximum increase in the thermal lens enhancement factor (by 40%) in comparison with unmodified aqueous solutions. The detection limit of iron(II) tris(1,10-phenanthrolinate) as a model system is 60 nM. Under these conditions, the thermal lens detection limit of hemichrome is 10 nM, which shows a 15-fold enhancement compared to spectro- photometry. Modification of the medium with polyethylene glycols decreases the limit of detection of hemichrome determination by 15% in comparison with unmodified aqueous solutions due to better reproducibility for the range of concentrations from 0.02 to 0.9 μM.
Keywords: Hemoglobin, hemikrom, optotermična spektroskopija, etilenglikol, spektrometrija s toplotnimi lečami
Published in RUNG: 16.04.2018; Views: 5116; Downloads: 0
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