Dr. Alicja Dabrowska Profile

Dr. Alicja Dabrowska

at Technische Univ Wien

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Author

Publications (4)

Proceedings Article | 17 March 2023 Presentation

Broadband mid-infrared milk protein analysis based on quantum cascade technology

Borislav Hinkov, Alicja Dabrowska, Mauro David, Andreas Schwaighofer, Stephan Freitag, Aaron Andrews, Gottfried Strasser, Bernhard Lendl

Proceedings Volume PC12430, PC124300E (2023) https://doi.org/10.1117/12.2650801

KEYWORDS: Proteins, Mid-IR, Spectrometers, Spectroscopy, Liquids, FT-IR spectroscopy, Spectroscopes, Sensors, Quantum chromodynamics, Quantum cascade lasers

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Proceedings Article | 8 March 2023 Presentation + Paper

Mid-IR photothermal sensing of liquids for trace analysis

Giovanna Ricchiuti, Alicja Dabrowska, Davide Pinto, Georg Ramer, Bernhard Lendl

Proceedings Volume 12428, 124280N (2023) https://doi.org/10.1117/12.2649811

KEYWORDS: Absorption, Quantum cascade lasers, Mid-IR, Bioalcohols, Liquids, Spectrometers, Mixtures, Matrices, Water, Spectroscopy

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Photothermal Spectroscopy (PTS) is an indirect analytical technique in which the optical signal is directly proportional to the laser emission intensity. This direct dependence on the laser power means that - in contrast to more conventional transmission-absorption techniques - PTS fully benefits from the high power of novel tunable mid-infrared laser sources such as Quantum Cascade Lasers (QCLs). In particular, QCLs equipped with an external cavity (EC) allow broad tunability which can be exploited in the detection of liquids identified by broad absorption bands. To achieve high sensitivity in PTS it is also important to choose a sensitive mode of transducing photothermal signal. Among the PTS transduction techniques photothermal interferometry (i.e. the detection of the phase change resulting from sample heating) stands out due to its high sensitivity. In this work, we use an EC-QCL in a photothermal interferometry PTS setup for trace water detection. We employ a HeNe laser-based Mach-Zehnder Interferometer (MZI) with liquid flow-cells inserted in the two arms. An EC-QCL emitting in the range of 1570-1730 cm^-1 is arranged co-linear to the analyte arm of the interferometer and used to target the bending mode (𝜈₂ ~ 1645 cm^-1) of water molecules in different matrices. Highest linearity and sensitivity are ensured by locking the MZI at its quadrature point via an active-feedback loop. Fluctuations and drifts are further minimized by means of temperature stabilization. When benchmarking the system against commercial FTIR spectrometers it is shown to be in excellent agreement with regards to band shapes, band positions and relative intensities and to compare favorably in terms of sensitivity. Achieved limits of detection (LODs) for water in chloroform and jet-fuel are in the low ppm range. Higher LODs orders of magnitude were obtained indeed for the case of water in ethanol. An analysis of the matrix influence on the PTS signal’s strength has been carried out. Results show how the choice of the matrix dramatically influences limits of detection and limits of quantification (LOQs).

Proceedings Article | 9 March 2022 Presentation

Octave-spanning long-range plasmonic waveguide based on semiconductor-loading for mid-infrared monolithic sensors

Mauro David, Alicja Dabrowska, Masiar Sistani, Erik Hinkelmann, Ismael Doganlar, Hermann Detz, Walter Weber, Bernhard Lendl, Gottfried Strasser, Borislav Hinkov

Proceedings Volume PC12021, PC120210N (2022) https://doi.org/10.1117/12.2610311

KEYWORDS: Mid-IR, Sensors, Semiconductors, Plasmonic waveguides, Plasmonics, Long wavelength infrared, Waveguides, Spectroscopy, Photonic integrated circuits, Infrared radiation

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Proceedings Article | 2 March 2022 Paper

The next generation of mid-IR laser-based refractive index (dispersion) spectroscopy of liquid-phase analytes

Alicja Dabrowska, Andreas Schwaighofer, Bernhard Lendl

Proceedings Volume 11957, 119570D (2022) https://doi.org/10.1117/12.2609371

KEYWORDS: Refractive index, Absorption, Spectroscopy, Dispersion, Interferometers, Interferometry, Sensors, Mid-IR, Glucose, Absorption spectroscopy

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Mid-infrared dispersion spectroscopy is a novel alternative approach to classical absorption spectroscopy for qualitative and quantitative analysis of liquid-phase samples focused on broadband refractive index variation sensing originating from IR absorption. We present the redesigned and improved version of an external cavity-quantum cascade laser-based MachZehnder interferometer setup dedicated for refractive index sensing of liquids, which outperforms classic absorption spectroscopy. The refined version of the setup features greater compactness, a new dual-channel transmission cell and a hysteresis-free piezo-actuator for phase locked interferometric detection. Moreover, a new routine for fast and almost simultaneous acquisition of real and imaginary part of the complex refractive index (i.e., dispersion and absorption spectra) was introduced for mutual validation of the spectra. Dispersion spectra at sample temperatures ranging from 15 to 90°C can be recorded as the setup shows a stable noise-floor over that temperature range. Introduction of a hysteresis-free piezoactuator to the system enabled fast spectral acquisition at constant sensitivity with speed rates of 100 cm^-1 /s, long-term stability and allowed to improve the reproducibility, robustness, and limits of detection of the method. We compare the performance of the refined setup with the previously demonstrated version by comparing the figures of merit for univariate glucose detection. In this context, the dispersion and absorption spectra of glucose were acquired and assessed. The achieved limit of detection for dispersion sensing was 5 times lower when compared to previous version and ~2 times lower than for classic absorption sensing at 5 times shorter spectra acquisition times. In summary, the improvements in the instrumentation for dispersion spectroscopy have improved the sensitivity, reliability, and quality of the method. The achieved results set a basis for further extension of the range of application presented for this technique.

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