Application: Time resolved vibrational spectroscopy
Product: IRis-F1
Karsten Hinrichs, Brianna Blevins, Andreas Furchner, Nataraja Yadavalli, Sergiy Minko, Raphael Horvath, Markus Mangold
Wiley Natural Sciences; 2023
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The mid-infrared (mid-IR) anisotropic optical response of a material probes vibrational fingerprints and absorption bands sensitive to order, structure and direction dependent stimuli. Such anisotropic properties play a fundamental role in catalysis, optoelectronic, photonic, polymer and biomedical research and applications. Infrared dual-comb polarimetry (IR-DCP) is introduced as a powerful new spectroscopic method for the analysis of complex dielectric functions and anisotropic samples in the mid-IR range. IR DCP enables novel hyperspectral and time-resolved applications far beyond the technical possibilities of classical Fourier-transform IR (FTIR) approaches. The method unravels structure–spectra relations at high spectral bandwidth (100 cm–1) and short integration times of 65 µs, with previously unattainable time resolutions for spectral IR polarimetric measurements for potential studies of noncyclic and irreversible processes. The polarimetric capabilities of IR-DCP are demonstrated by investigating an anisotropic inhomogeneous free-standing nanofiber scaffold for neural tissue applications. Polarization sensitive multi-angle dual-comb transmission amplitude and absolute phase measurements (separately for ss-, pp-, ps- and sp-polarized light) allow the in-depth probing of the samples’ orientation dependent vibrational absorption properties. Mid-IR anisotropies can be quickly identified by cross-polarized IR-DCP polarimetry.
Application: Gas analysis, High resolution spectroscopy, Time resolved vibrational spectroscopy
Product: IRis-F1
Josef A. Agner, Sieghard Albert, Pitt Allmendinger, Urs Hollenstein, Andreas Hugi, Pierre Jouy, Karen Keppler, Markus Mangold, Frédéric Merkt & Martin Quack
Molecular Physics; 2022
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Optical frequency-comb spectroscopy has proven a very useful tool for high-resolution molecular spectroscopy. Frequency combs based on quantum-cascade lasers (QCL) offer the possibility to easily explore the mid-infrared spectral range (4 µm to 12 µm), but are characterised by large repetition frequencies (∼ 10 GHz) which make them seemingly unsuitable for high-resolution spectroscopy. Here, we present techniques to overcome this limitation. We have employed the combined advantages of high temporal and high spectral resolution to measure the infrared (IR) spectra of CF4 and CHCl2F in pulsed, skimmed supersonic beams. The low rotational temperature of the beams and the narrow expansion cone after the skimmer enabled the recording of spectra of cold samples with high resolution. The spectra cover the range from 1200 cm−1 to 1290 cm−1 and the narrowest lines have a full width at half maximum of 15 MHz, limited by the Doppler effect. The results demonstrate the potential of QCL dual-comb spectroscopy for broadband (> 60 cm−1) acquisition of spectra at high spectral (better than 5·10−4 cm−1, 15 MHz) and temporal (better than 4 µs) resolution and high sensitivity in the mid-infrared range. The power of the new technology is demonstrated by comparison with previous results for these molecules obtained by FTIR and diode laser spectroscopy.
Application: Photochemistry and photocatalysis, Protein dynamics, Time resolved vibrational spectroscopy
Product: IRis-F1
Luiz Schubert, Pit Langner, David Ehrenberg, Victor A. Lorenz-Fonfria, and Joachim Heberle
The Journal of Chemical Physics; 2022
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Mid-IR spectroscopy is a powerful and label-free technique to investigate protein reactions. In this study, we use quantum-cascade-laser-based dual-comb spectroscopy to probe protein conformational changes and protonation events by a single-shot experiment. By using a well-characterized membrane protein, bacteriorhodopsin, we provide a comparison between dual-comb spectroscopy and our homebuilt tunable quantum cascade laser (QCL)-based scanning spectrometer as tools to monitor irreversible reactions with high time resolution. In conclusion, QCL-based infrared spectroscopy is demonstrated to be feasible for tracing functionally relevant protein structural changes and proton translocations by single-shot experiments. Thus, we envisage a bright future for applications of this technology for monitoring the kinetics of irreversible reactions as in (bio-)chemical transformations.
Application: Spectroelectrochemistry, Time resolved vibrational spectroscopy
Product: IRis-F1
Lins, E.; Read, S.; Unni, B.; Rosendahl, S. M.; Burgess, I. J.
Analytical Chemistry; 2020
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A dual infrared frequency comb spectrometer with heterodyne detection has been used to perform time-resolved electrochemical attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS). The measurement of the potential dependent desorption of a monolayer of a pyridine derivative (4-dimethylaminopyridine, DMAP) with time resolution as high as 4 μs was achieved without the use of step-scan interferometry. An analysis of the detection limit of the method as a function of both time resolution and measurement coadditions is provided and compared to step-scan experiments of an equivalent system. Dual frequency comb spectroscopy is shown to be highly amenable to time-resolved ATR-SEIRAS. Microsecond resolved spectra can be obtained with high spectral resolution and fractional monolayer detection limits in a total experimental duration that is 2 orders of magnitude less than the equivalent step-scan experiment.
Application: Combustion diagnostics, Shock tubes and rapid compression machines, Time resolved vibrational spectroscopy
Product: IRis-F1
Pinkowski, Nicolas Hunter; Ding, Yiming; Strand, Christopher L.; Hanson, Ronald K.; Horvarth, Raphael; Geiser, Markus
Measurement Science and Technology; 2020
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In the current study, a quantum-cascade-laser-based dual-comb spectrometer (DCS) was used to paint a detailed picture of a 1.0 ms high-temperature reaction between propyne and oxygen. The DCS interfaced with a shock tube to provide pre-ignition conditions of 1225 K, 2.8 atm, and 2% p-C3H4/18% O2/Ar. The spectrometer consisted of two free-running, non-stabilized frequency combs each emitting at 179 wavelengths between 1174 and 1233 cm−1. A free spectral range, {f_r}, of 9.86 GHz and a difference in comb spacing, {Delta }{f_r}, of 5 MHz, enabled a theoretical time resolution of 0.2 µs but the data was time-integrated to 4 µs to improve SNR. The accuracy of the spectrometer was monitored using a suite of independent laser diagnostics and good agreement observed. Key challenges remain in the fitting of available high-temperature spectroscopic models to the observed spectra of a post-ignition environment.
Application: Combustion diagnostics, Shock tubes and rapid compression machines, Time resolved vibrational spectroscopy
Product: IRis-F1
Guangle Zhang, Raphael Horvath, Dapeng Liu, Markus Geiser, Aamir Farooq
Sensors, MDPI; 2020
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Rapid multi-species sensing is an overarching goal in time-resolved studies of chemical kinetics. Most current laser sources cannot achieve this goal due to their narrow spectral coverage and/or slow wavelength scanning. In this work, a novel mid-IR dual-comb spectrometer is utilized for chemical kinetic investigations. The spectrometer is based on two quantum cascade laser frequency combs and provides rapid (4 µs) measurements over a wide spectral range (~1175–1235 cm−1). Here, the spectrometer was applied to make time-resolved absorption measurements of methane, acetone, propene, and propyne at high temperatures (>1000 K) and high pressures (>5 bar) in a shock tube. Such a spectrometer will be of high value in chemical kinetic studies of future fuels.
Application: Combustion diagnostics, Shock tubes and rapid compression machines, Time resolved vibrational spectroscopy
Product: IRis-F1
Pinkowski, N.; Strand, C. L.; Ding, Y.; Hanson, R. K.; Geiser, M.; Horvath, R.
Presentation at ISSW32; 2019
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Application: Photochemistry and photocatalysis, Protein dynamics, Time resolved vibrational spectroscopy
Product: IRis-F1
Geiser, Markus; Klocke, Jessica L.; Mangold, Markus; Allmendinger, Pitt; Hugi, Andreas; Jouy, Pierre; Horvath, Balint; Faist, Jerome; Kottke, Tilman
Biophysical Journal, Elsevier; 2018
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Time-resolved vibrational spectroscopy is an important tool for understanding biological processes and chemical reaction pathways. Today, all available methods to our knowledge require many repetitions of an experiment to acquire a microsecond time-res. mid-IR spectrum. We present the IRspectrometer, a quantum cascade laser dual frequency comb spectrometer. It allows for parallel acquisition of hundreds of mid-infrared wavelengths with microsecond time resolution. The formation of the light-activated L, M and N-states in bacteriorhodopsin - which only have µs to ms lifetimes - has been recorded with our setup: e.g. infrared response of bacteriorhodopsin to 10 ns visible light pulses with microsecond time-resolution. The different wavelengths were all measured in parallel thanks to the dual-comb approach. The spectra as well as the kinetics show good agreement with those from step-scan FTIR measurements. As a benchmark, the spectral signature of several intermediate states of the bacteriorhodopsin photocycle has been recorded in a single shot measurement. This approach greatly reduces the complexity of time-resolved bio-spectroscopy measurements in the mid-infrared which currently require many repetitions.
Application: Time resolved vibrational spectroscopy
Product: IRis-F1
Dr. Florian Eigenmann and Dr. Raphael Horvath
China Coatings Journal; 2020
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