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Furchner A, Kratz C, Rappich J, Hinrichs K. Multi-timescale infrared quantum cascade laser ellipsometry. OPTICS LETTERS 2022; 47:2834-2837. [PMID: 35648942 DOI: 10.1364/ol.457688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
We recently introduced a novel, to the best of our knowledge, infrared laser ellipsometer for sub-decisecond spectroscopy [Opt. Lett.44, 4387 (2019)10.1364/OL.44.004387] and 0.03 mm2 spot-sized hyperspectral imaging [Opt. Lett.44, 4893 (2019)10.1364/OL.44.004893]. Here we report on the next device generation for thin-film sensitive simultaneous single-shot amplitude and phase measurements. The multi-timescale ellipsometer achieves 10 µs time resolution and long-term stability over hours at high spectral resolution (0.2 cm-1). We investigate the temporal stages (from minutes to milliseconds) of fatty acid thin-film formation upon solvent evaporation from acetone-diluted microliter droplets. Optical thickness variations, structure modifications, and molecular interactions are probed during the liquid-to-solid phase transition. Multi-timescale ellipsometry could greatly impact fields like in situ biosensing, microfluidics, and polymer analytics, but also operando applications in membrane research, catalysis, and studies of interface processes and surface reactions.
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Ebner A, Zimmerleiter R, Hingerl K, Brandstetter M. Towards Real-Time In-Situ Mid-Infrared Spectroscopic Ellipsometry in Polymer Processing. Polymers (Basel) 2021; 14:7. [PMID: 35012030 PMCID: PMC8747145 DOI: 10.3390/polym14010007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 01/13/2023] Open
Abstract
Recent developments in mid-infrared (MIR) spectroscopic ellipsometry enabled by quantum cascade lasers (QCLs) have resulted in a drastic improvement in signal-to-noise ratio compared to conventional thermal emitter based instrumentation. Thus, it was possible to reduce the acquisition time for high-resolution broadband ellipsometric spectra from multiple hours to less than 1 s. This opens up new possibilities for real-time in-situ ellipsometry in polymer processing. To highlight these evolving capabilities, we demonstrate the benefits of a QCL based MIR ellipsometer by investigating single and multilayered polymer films. The molecular structure and reorientation of a 2.5 µm thin biaxially oriented polyethylene terephthalate film is monitored during a stretching process lasting 24.5 s to illustrate the perspective of ellipsometric measurements in dynamic processes. In addition, a polyethylene/ethylene vinyl alcohol/polyethylene multilayer film is investigated at a continuously varying angle of incidence (0∘- 50∘) in 17.2 s, highlighting an unprecedented sample throughput for the technique of varying angle spectroscopic ellipsometry in the MIR spectral range. The obtained results underline the superior spectral and temporal resolution of QCL ellipsometry and qualify this technique as a suitable method for advanced in-situ monitoring in polymer processing.
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Affiliation(s)
- Alexander Ebner
- RECENDT—Research Center for Non-Destructive Testing GmbH, 4040 Linz, Austria; (A.E.); (R.Z.)
| | - Robert Zimmerleiter
- RECENDT—Research Center for Non-Destructive Testing GmbH, 4040 Linz, Austria; (A.E.); (R.Z.)
| | - Kurt Hingerl
- Center for Surface and Nanoanalytics, Johannes Kepler University, 4040 Linz, Austria;
| | - Markus Brandstetter
- RECENDT—Research Center for Non-Destructive Testing GmbH, 4040 Linz, Austria; (A.E.); (R.Z.)
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Freitag S, Baer M, Buntzoll L, Ramer G, Schwaighofer A, Schmauss B, Lendl B. Polarimetric Balanced Detection: Background-Free Mid-IR Evanescent Field Laser Spectroscopy for Low-Noise, Long-term Stable Chemical Sensing. ACS Sens 2021; 6:35-42. [PMID: 33372759 PMCID: PMC7872502 DOI: 10.1021/acssensors.0c01342] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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In
this work, we introduce polarimetric balanced detection as a
new attenuated total reflection (ATR) infrared (IR) sensing scheme,
leveraging unequal effective thicknesses achieved with laser light
of different polarizations. We combined a monolithic widely tunable
Vernier quantum cascade laser (QCL-XT) and a multibounce ATR IR spectroscopy
setup for analysis of liquids in a process analytical setting. Polarimetric
balanced detection enables simultaneous recording of background and
sample spectra, significantly reducing long-term drifts. The root-mean-square
noise could be improved by a factor of 10 in a long-term experiment,
compared to conventional absorbance measurements obtained via the
single-ended optical channel. The sensing performance of the device
was further evaluated by on-site measurements of ethanol in water,
leading to an improved limit of detection (LOD) achieved with polarimetric
balanced detection. Sequential injection analysis was employed for
automated injection of samples into a custom-built ATR flow cell mounted
above a zinc sulfide multibounce ATR element. The QCL-XT posed to
be suitable for mid-IR-based sensing in liquids due to its wide tunability.
Polarimetric balanced detection proved to enhance the robustness and
long-term stability of the sensing device, along with improving the
LOD by a factor of 5. This demonstrates the potential for new polarimetric
QCL-based ATR mid-IR sensing schemes for in-field measurements or
process monitoring usually prone to a multitude of interferences.
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Affiliation(s)
- Stephan Freitag
- Institute of Chemical Technologies and Analytics, Technische Universität Wien, Getreidemarkt 9/164-UPA, 1060 Vienna, Austria
| | - Matthias Baer
- Institute of Microwaves and Photonics, Friedrich-Alexander-University Erlangen-Nuremberg, Cauerstr. 9, 91058 Erlangen, Germany
| | - Laura Buntzoll
- Institute of Microwaves and Photonics, Friedrich-Alexander-University Erlangen-Nuremberg, Cauerstr. 9, 91058 Erlangen, Germany
| | - Georg Ramer
- Institute of Chemical Technologies and Analytics, Technische Universität Wien, Getreidemarkt 9/164-UPA, 1060 Vienna, Austria
| | - Andreas Schwaighofer
- Institute of Chemical Technologies and Analytics, Technische Universität Wien, Getreidemarkt 9/164-UPA, 1060 Vienna, Austria
| | - Bernhard Schmauss
- Institute of Microwaves and Photonics, Friedrich-Alexander-University Erlangen-Nuremberg, Cauerstr. 9, 91058 Erlangen, Germany
| | - Bernhard Lendl
- Institute of Chemical Technologies and Analytics, Technische Universität Wien, Getreidemarkt 9/164-UPA, 1060 Vienna, Austria
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Romanenko A, Kalas B, Hermann P, Hakkel O, Illés L, Fried M, Fürjes P, Gyulai G, Petrik P. Membrane-Based In Situ Mid-Infrared Spectroscopic Ellipsometry: A Study on the Membrane Affinity of Polylactide- co-glycolide Nanoparticulate Systems. Anal Chem 2020; 93:981-991. [PMID: 33315391 PMCID: PMC7872323 DOI: 10.1021/acs.analchem.0c03763] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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Mid-infrared (IR) ellipsometry of
thin films and molecule layers
at solid–liquid interfaces has been a challenge because of
the absorption of light in water. It has been usually overcome by
using configurations utilizing illumination through the solid substrate.
However, the access to the solid–liquid interface in a broad
spectral range is also challenging due to the limited transparency
of most structural materials in the IR wavelength range. In this work,
we propose a concept of a microfabricated analysis cell based on an
IR-transparent Si membrane with advantages of a robust design, flexible
adaptation to existing equipment, small volume, multiple-angle capabilities,
broad wavelength range, and opportunities of multilayer applications
for adjusted ranges of high sensitivity. The chamber was prepared
by 3D micromachining technology utilizing deep reactive ion etching
of a silicon-on-insulator wafer and bonded to a polydimethylsiloxane
microfluidic injection system resulting in a cell volume of approximately
50 μL. The mechanical stability of the 2 and 5 μm-thick
membranes was tested using different “backbone” reinforcement
structures. It was proved that the 5 μm-thick membranes are
stable at lateral cell sizes of 5 mm by 20 mm. The cell provides good
intensity and adjustment capabilities on the stage of a commercial
mid-IR ellipsometer. The membrane configuration also provides optical
access to the sensing interfaces at a broad range of incident angles,
which is a significant advantage in many potential sensing structure
configurations, such as plasmonic, multilayer, 2D, or metamaterial
applications.
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Affiliation(s)
- Alekszej Romanenko
- Centre for Energy Research, Konkoly Thege Miklós út 29-33, H-1121 Budapest, Hungary.,Doctoral School of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary
| | - Benjamin Kalas
- Centre for Energy Research, Konkoly Thege Miklós út 29-33, H-1121 Budapest, Hungary
| | - Petra Hermann
- Centre for Energy Research, Konkoly Thege Miklós út 29-33, H-1121 Budapest, Hungary
| | - Orsolya Hakkel
- Centre for Energy Research, Konkoly Thege Miklós út 29-33, H-1121 Budapest, Hungary
| | - Levente Illés
- Centre for Energy Research, Konkoly Thege Miklós út 29-33, H-1121 Budapest, Hungary
| | - Miklós Fried
- Centre for Energy Research, Konkoly Thege Miklós út 29-33, H-1121 Budapest, Hungary.,Institute of Microelectronics and Technology, Óbuda University, Tavaszmezö u. 17, H-1084 Budapest, Hungary
| | - Peter Fürjes
- Centre for Energy Research, Konkoly Thege Miklós út 29-33, H-1121 Budapest, Hungary
| | - Gergö Gyulai
- Laboratory of Interfaces and Nanostructures, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary
| | - Peter Petrik
- Centre for Energy Research, Konkoly Thege Miklós út 29-33, H-1121 Budapest, Hungary
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Kratz C, Furchner A, Sun G, Rappich J, Hinrichs K. Sensing and structure analysis by in situIR spectroscopy: from mL flow cells to microfluidic applications. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:393002. [PMID: 32235045 DOI: 10.1088/1361-648x/ab8523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/31/2020] [Indexed: 06/11/2023]
Abstract
In situmid-infrared (MIR) spectroscopy in liquids is an emerging field for the analysis of functional surfaces and chemical reactions. Different basic geometries exist forin situMIR spectroscopy in milliliter (mL) and microfluidic flow cells, such as attenuated total reflection (ATR), simple reflection, transmission and fiber waveguides. After a general introduction of linear opticalin situMIR techniques, the methodology of ATR, ellipsometric and microfluidic applications in single-reflection geometries is presented. Selected examples focusing on thin layers relevant to optical, electronical, polymer, biomedical, sensing and silicon technology are discussed. The development of an optofluidic platform translates IR spectroscopy to the world of micro- and nanofluidics. With the implementation of SEIRA (surface enhanced infrared absorption) interfaces, the sensitivity of optofluidic analyses of biomolecules can be improved significantly. A large variety of enhancement surfaces ranging from tailored nanostructures to metal-island film substrates are promising for this purpose. Meanwhile, time-resolved studies, such as sub-monolayer formation of organic molecules in nL volumes, become available in microscopic or laser-based set-ups. With the adaption of modern brilliant IR sources, such as tunable and broadband IR lasers as well as frequency comb sources, possible applications of far-field IR spectroscopy inin situsensing with high lateral (sub-mm) and time (sub-s) resolution are considerably extended.
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Affiliation(s)
| | | | - Guoguang Sun
- ISAS-e.V., Schwarzschildstr. 8, 12489 Berlin, Germany
| | - Jörg Rappich
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Kekuléstr. 5, 12489 Berlin, Germany
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Furchner A, Kratz C, Rappich J, Hinrichs K. Hyperspectral infrared laser polarimetry for single-shot phase-amplitude imaging of thin films. OPTICS LETTERS 2019; 44:4893-4896. [PMID: 31568469 DOI: 10.1364/ol.44.004893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 08/29/2019] [Indexed: 06/10/2023]
Abstract
We recently presented a novel laser-based infrared (IR) spectroscopic phase-amplitude polarimeter for sub-decisecond and sub-mm2 measurements of organic thin films [Opt. Lett.44, 4387 (2019)OPLEDP0146-959210.1364/OL.44.004387]. Here we report on the hyperspectral-imaging capabilities of this device. The single-shot polarimeter employs a broadly tunable mid-IR (1318-1765 cm-1) quantum cascade laser (QCL) and a four-channel beam-division design for simultaneous phase and amplitude measurements. Fast QCL tuning speeds of up to 1500 cm-1/s enable hyperspectral mapping of large sample areas (50×50 mm2) within several tens of minutes, achieving 120 μm spatial and <0.5 cm-1 spectral resolution. We apply the instrument for imaging both the heterogeneous chemical and structural properties of sub-100 nm thin polymer and fatty-acid films. Our polarimeter opens up new applications regarding laterally resolved IR analyses of complex thin films.
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