1. Pump-probe photothermal self-mixing system for highly sensitive trace detectionDorota Korte, Humberto Cabrera, Evelio E. Ramırez-Miquet, Joseph J. Niemela, Jose Juan Suárez-Vargas, John Fredy Barrera Ramırez, 2018, original scientific article Found in: ključnih besedah
Keywords: thermal lens, self-mixing interferometry, trace
detection
Published: 01.03.2019; Views: 2223; Downloads: 0
 Fulltext (819,63 KB) |
2. Photothermal lens technique: a comparison between conventional and self-mixing schemesJohn Fredy Barrera Ramírez, Dorota Korte, Jose Juan Suárez-Vargas, Jehan Akbar, Evelio E. Ramírez-Miquet, Fatima Matroodi, Imrana Ashraf, Humberto Cabrera, Hanna Budasheva, Joseph J. Niemela, 2019, original scientific article Abstract: This work focuses on assessing the analytical capabilities of a new photothermal lens method based on the self-mixing effect to reliably measure metallic traces in water-ethanol solutions. We compare it with the conventional thermal lens scheme, considering the low detection limit and versatility. A theoretical model is presented to describe the laser power variations as a function of the photothermal parameters of the analyzed sample. The experimental results demonstrate that the laser intensity variations, induced by the external optical feedback, are governed by
the photothermal lens effect. Measurements of Fe(II)-1,10-phenanthroline in water–ethanol solutions show a favourable correspondence and agreement with the theory. The low detection limits obtained by the two analytic techniques also agree very well. Nevertheless, our instrument presents advantages regarding compactness and simplicity, suggesting that this platform could be potentially useful as a robust analytical tool for metallic trace detection. In addition, calibration of the method is performed by measuring the so-called self-mixing constant.
Found in: ključnih besedah
Summary of found: ...the self-mixing effect to reliably measure metallic traces in water-ethanol solutions. We compare it with... ...conventional thermal lens scheme, considering the low detection limit and versatility. A theoretical model is...
Keywords: thermal lens, photothermal spectroscopy, self-mixing effect, trace detection
Published: 05.04.2019; Views: 2124; Downloads: 0
Fulltext (715,09 KB) |
3. A multi-thermal-lens approach to evaluation of multi-pass probe beam configuration in thermal lens spectrometryHumberto Cabrera, Leja Goljat, Dorota Korte, Ernesto Marin, Mladen Franko, original scientific article Abstract: 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.
Found in: ključnih besedah
Summary of found: ...Thermal lens spectrometry, Photothermal detection, Trace determination, Chemical sensor...
Keywords: Thermal lens spectrometry, Photothermal detection, Trace determination, Chemical sensor
Published: 10.12.2019; Views: 1876; Downloads: 0
Fulltext (656,75 KB) |
