ǂA ǂmulti-thermal-lens approach to evaluation of multi-pass probe beam configuration in thermal lens spectrometry
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.
Keywords
thermal lens spectrometry;photothermal detection;trace determination;chemical sensor;
Data
| Language: | English |
|---|---|
| Year of publishing: | 2020 |
| Typology: | 1.01 - Original Scientific Article |
| Organization: | UNG - University of Nova Gorica |
| UDC: | 54 |
| COBISS: |
5499131
|
| ISSN: | 0003-2670 |
| Views: | 2501 |
| Downloads: | 0 |
| Average score: | 0 (0 votes) |
| Metadata: |
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Other data
| URN: | URN:SI:UNG |
|---|---|
| Type (COBISS): | Not categorized |
| Pages: | str. 182-190 |
| Issue: | ǂVol. ǂ1100 |
| Chronology: | Mar. 2020 |
| DOI: | 10.1016/j.aca.2019.12.009 |
| ID: | 11327907 |
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