Lecture
Advancing mid-IR spectroscopy of liquids using broadly tuneable laser sources
- at -
- ICM Saal 5
- Type: Lecture
Lecture description
B. Lendl, Vienna /AT, A. Dabrowska, Vienna /AT, D. Mauro, Vienna /AT, G. Ramer Vienna /AT, D. Tomasetig Vienna /AT, J. H. Mendoza-Castro, Vienna /AT, A. S. Vorobev, Cork/Ireland, L. O’Faolain, Cork/Ireland
Advances in Instrumental Analytical Chemistry are often linked to technological developments in neighbouring disciplines. This is the case with respect to recent advances in mid-IR quantum cascade lasers (QCLs) which are increasingly used as light sources in mid-IR spectroscopy. QCLs offer high spectral power densities, fast amplitude and frequency modulation possibilities, polarized and coherent radiation. Based on these properties a range of new sensing schemes, often clearly outperforming established FTIR spectrometers, can be developed.
This presentation will introduce dispersion spectroscopy implemented in a free space optics Mach Zehnder Interferometer will be introduced for measuring the real part of the complex refractive index of liquid samples. The proposed design is made possible by
the coherent nature of the light provided by the EC-QCL. Dispersion spectroscopy has several advantages over absorbance spectroscopy: It is a baseline free technique, the reading is independent of power fluctuations of the laser source, and the recorded
signal is direct proportional to the analyte concentration hence providing constant sensitivity over a large concentration range. [1]
EC-QCL photothermal spectroscopy of liquids will be introduced by showing applications of photothermal lens and photothermal mirror techniques for the determination of water traces in aqueous solutions. In this case absorption induced heating and the resulting changes in the sample´s refractive index are probed by a second visible probe laser beams.
Finally, efforts will be reported on integration of the introduced sensing principles on photonic integrated chips (PICs) where we are using Mach-Zehnder interferometers, ring resonators as well as nanobeams integrated on a SiN on SOI (silicon on isolator) platform with readout in the NIR spectral region (C-band) as transducer for absorption induced refractive index changes. [2]
Literature:
[1] A. Dabrowska, S. Lindner, A. Schwaighofer, B. Lendl, Spectrochim. Acta Part A: Mol. and Biomol. Spectrosc. 2023, 286, 122014
[2] D. Tomasetig, J.H. MendozaCastro, S. Schobesberger, A.S. Vorobev, L. O′Faolain, B. Lendl, ACS Meas. Sci. Au, 2026, DOI: 10.1021/acsmeasuresciau.5c00139
Advances in Instrumental Analytical Chemistry are often linked to technological developments in neighbouring disciplines. This is the case with respect to recent advances in mid-IR quantum cascade lasers (QCLs) which are increasingly used as light sources in mid-IR spectroscopy. QCLs offer high spectral power densities, fast amplitude and frequency modulation possibilities, polarized and coherent radiation. Based on these properties a range of new sensing schemes, often clearly outperforming established FTIR spectrometers, can be developed.
This presentation will introduce dispersion spectroscopy implemented in a free space optics Mach Zehnder Interferometer will be introduced for measuring the real part of the complex refractive index of liquid samples. The proposed design is made possible by
the coherent nature of the light provided by the EC-QCL. Dispersion spectroscopy has several advantages over absorbance spectroscopy: It is a baseline free technique, the reading is independent of power fluctuations of the laser source, and the recorded
signal is direct proportional to the analyte concentration hence providing constant sensitivity over a large concentration range. [1]
EC-QCL photothermal spectroscopy of liquids will be introduced by showing applications of photothermal lens and photothermal mirror techniques for the determination of water traces in aqueous solutions. In this case absorption induced heating and the resulting changes in the sample´s refractive index are probed by a second visible probe laser beams.
Finally, efforts will be reported on integration of the introduced sensing principles on photonic integrated chips (PICs) where we are using Mach-Zehnder interferometers, ring resonators as well as nanobeams integrated on a SiN on SOI (silicon on isolator) platform with readout in the NIR spectral region (C-band) as transducer for absorption induced refractive index changes. [2]
Literature:
[1] A. Dabrowska, S. Lindner, A. Schwaighofer, B. Lendl, Spectrochim. Acta Part A: Mol. and Biomol. Spectrosc. 2023, 286, 122014
[2] D. Tomasetig, J.H. MendozaCastro, S. Schobesberger, A.S. Vorobev, L. O′Faolain, B. Lendl, ACS Meas. Sci. Au, 2026, DOI: 10.1021/acsmeasuresciau.5c00139
