Ricchiuti, Giovanna

Dabrowska, Alicja

Pinto, Davide

Ramer, Georg

Lendl, Bernhard

2023-02-02T09:59:15Z

2023-02-02T09:59:15Z

2022-09

<div class="csl-bib-body"> <div class="csl-entry">Ricchiuti, G., Dabrowska, A., Pinto, D., Ramer, G., &#38; Lendl, B. (2022, September). <i>A Dual-beam Photothermal Mach-Zehnder Interferometer Employing an External Cavity Quantum Cascade Laser for Detection of Water Traces in Organic Solvents</i> [Conference Presentation]. FLAIR 2022, Aix-les-Bains, France. http://hdl.handle.net/20.500.12708/148090</div> </div>

http://hdl.handle.net/20.500.12708/148090

Mid-infrared (mid-IR) spectroscopy is a versatile analytical technique that allows for qualitative and quantitative analysis. It is based on probing highly selective rotational and vibrational transitions of analyte molecules present in gases, liquids and solids. [1] Classical absorption spectroscopy based on Lambert-Beer´s law relies on detection of minute differences in light intensity. However, as absorbance does not scale with laser power it does not fully benefit from quantum cascade lasers’ (QCLs) high power and brilliance. [2] At the contrary, photothermal spectroscopy (PTS) is an indirect detection approach where the generated analytical signal is directly proportional to the applied laser power. [3] In this work, we present a photothermal mid-IR spectroscopy setup that achieves low-ppm range limits of detection for water in organic solvents (ethanol and chloroform) and as a most difficult application in aircraft’s jet fuel. The device has been calibrated and validated against coulometric Karl Fischer titration (KF) and is shown to have comparable performance and sensitivity. In contrast to KF, the spectroscopic nature of the sensor allows to gain additional information on the analyte and works reagent-free.

We present a mid-IR laser-based photothermal spectroscopy (PTS) setup for the analysis of liquids on the example of sensitive detection of water traces in organic solvents (ethanol and chloroform) and as a most difficult application in aircraft’s jet fuel. The presented sensor system works reagent free and can be applied in an on-line format in the chemical industry as well as for fuel quality control, being industrial applications where traces of water need to be accurately determined, preferably in real-time. It thus holds great promise to replace the off-line Karl-Fischer titration method which is the current standard method for this application, but which entails important drawbacks such as being time consuming, requiring toxic reagents and producing waste. In PTS the sample is illuminated by a pulsed mid-IR excitation source causing a periodical heating and cooling of the sample. The resulting photo-induced thermal gradient ΔT can be probed as a consequent refractive index change (Δn) by means of a second laser source, a so called “probe laser”. The challenge lies in detecting the smallest Δn. To do that, we use an interferometric approach. In particular, our latest generation liquid PTS IR sensor consists of a Mach-Zehnder Interferometer (MZI) able to sense sub-nm phase shifts Δφ between its two arms. In detail, we use a HeNe probe laser and an external cavity (EC)-QCL pump laser tuneable from 1730 to 1565 cm-1. The stability and linearity of our system are ensured by temperature stabilization and holding the MZI in its quadrature point using a PID controlled piezo electric transducer (PZT) glued directly on a mirror in one arm of the MZI. Some of the relevant obtained results are reported in Fig. 1. Achieved limits of detection are in the low ppm region.

European Commission

en

Photothermal Spectroscopy

PAT

A Dual-beam Photothermal Mach-Zehnder Interferometer Employing an External Cavity Quantum Cascade Laser for Detection of Water Traces in Organic Solvents

Presentation

Vortrag

860808

Conference Presentation

European Joint Doctorate Programme on Optical Sensing using Advanced Photo-Induced Effects

M2

Q1

I8

Materials Characterization

Photonics

Sensor Systems

10

60

30

E164-02-1 - Forschungsgruppe Prozessanalytik

0000-0002-0586-1841

0000-0002-3074-5674

0000-0002-6021-4997

0000-0001-8307-5435

0000-0003-3838-5842

FLAIR 2022

12-09-2022

16-09-2022

On Site

Event for scientific audience

Aix-les-Bains

FR

Ricchiuti, Giovanna

Single Track

Chemie

Chemische Verfahrenstechnik

Physik, Astronomie

1040

2040

1030

60

15

25

restricted

http://purl.org/coar/resource_type/c_18cp

conference paper not in proceedings

Publications

no Fulltext

en

E164-02-1 - Forschungsgruppe Prozessanalytik

E164-02-1 - Forschungsgruppe Prozessanalytik

E164-02-1 - Forschungsgruppe Prozessanalytik

E164-02-1 - Forschungsgruppe Prozessanalytik

E164-02 - Forschungsbereich Umwelt-, Prozessanalytik und Sensoren

0000-0002-0586-1841

0000-0002-3074-5674

0000-0002-6021-4997

0000-0001-8307-5435

0000-0003-3838-5842

E164-02 - Forschungsbereich Umwelt-, Prozessanalytik und Sensoren

E164-02 - Forschungsbereich Umwelt-, Prozessanalytik und Sensoren

E164-02 - Forschungsbereich Umwelt-, Prozessanalytik und Sensoren

E164-02 - Forschungsbereich Umwelt-, Prozessanalytik und Sensoren

E164 - Institut für Chemische Technologien und Analytik

European Commission

860808