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Abstract: In the paper the optimization of the experimental setup for photothermal beam deflection spectrometry is performed by analyzing the influence of its geometrical parameters (detector and sample position, probe beam radius and its waist position etc) on the detected signal. Furthermore, the effects of fluid’s thermo-optical properties, for optimized geometrical configuration, on the measurement sensitivity and uncertainty determination of sample thermal properties is also studied. The examined sample is a recently developed CuFeInTe3 material. Results show, that it is a complex problem to choose the proper geometrical configuration as well as sensing fluid to enhance the sensitivity of the method. A signal enhancement is observed at low modulation frequencies by placing the sample in acetonitrile (ACN), while at high modulation frequencies the sensitivity is higher for measurements made in air. For both, detection in air and acetonitrile the determination of CuFeInTe3 thermal properties is performed. The determined values of thermal diffusivity and thermal conductivity are (0.048 ± 0.002) × 10−4 m2 s−1 and 4.6 ± 0.2 W m−1 K−1 and (0.056 ± 0.005) × 10−4 m2 s−1 and 4.8 ± 0.4 W m−1 K−1 for ACN and air, respectively. It is seen, that the determined values agree well within the range of their measurement uncertainties for both cases, although the measurement uncertainty is two times lower for the measurements in ACN providing more accurate results. The analysis is performed by the use of recently developed theoretical description based on the complex geometrical optics. It is also shown, how the presented work fits into the current status of photothermal beam deflection spectroscopy.
Found in: osebi
Keywords: Optitermi, na spektrometrija, toplotna difuzivnost, toplotna prevodnost, polprevodniki, vpliv topila
Published: 07.11.2016; Views: 3892; Downloads: 0
Fulltext (2,15 MB)

Found in: osebi
Keywords: AMPLIEFIED THERMAL LENS SPECTROMETRY, Fe2+
Published: 30.08.2017; Views: 3554; Downloads: 0
Fulltext (12,87 MB)

Found in: osebi
Keywords: thermal properties, Photothermal radiometry, beam deflection spectrometry, thermal lens spectrometry, thermoreflectance
Published: 30.06.2022; Views: 408; Downloads: 26
Fulltext (219,73 KB)

Abstract: 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.
Found in: osebi
Keywords: thermal lens spectrometry, Fe(II) determination, photothermal technique, multi-wavelength excitation
Published: 21.02.2018; Views: 3207; Downloads: 0
Fulltext (889,82 KB)

Found in: osebi
Keywords: Thermal lens spectrometry, Photothermal beam deflection spectroscopy, Dye remediation, Photothermal technique, Photocatalytic degradation, Reactive Blue 19, TiO2 modification
Published: 09.11.2018; Views: 2795; Downloads: 0
Fulltext (208,76 KB)