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Biermann M, Leppin C, Langhoff A, Ziemer T, Rembe C, Johannsmann D. An electrochemical quartz crystal microbalance (EQCM) based on microelectrode arrays allows to distinguish between adsorption and electrodeposition. Analyst 2024; 149:2138-2146. [PMID: 38436402 DOI: 10.1039/d3an02210b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
Using a precise electrochemical quartz crystal microbalance (EQCM), it was shown that electrogravimetry can be carried out with microelectrode arrays (MEAs). MEAs were prepared on the resonator surface by coating it with a thin polymer layer containing holes, where the holes constitute the microelectrodes. The preparation procedures, their benefits, and their limitations are discussed. Microelectrode-based electrogravimetry is challenging because the reduced active area reduces the QCM signal. It is still feasible. This work is limited to linear voltage ramps (as opposed to steps). The processes chosen for demonstration were the electrodeposition/stripping of copper and the redox cycling of methyl viologen dichloride (MVC). The current trace often showed microelectrodic behavior, depending on the sweep rate. For the case of copper deposition, the mass transfer rate was proportional to the electric current. For the case of MVC, the electric current showed a plateau at the ends of the current-voltage diagram, but the mass transfer rate did not change. The difference can be explained by adsorption and desorption going into saturation at the two ends of the voltage range. Based on whether or not a microelectrodic gravimetric signal is seen, it can be stated whether the mass transfer is closely linked to the current. Further advantages of the microelectrode-based EQCM are an improved access to fast processes, reduced effects of double layer recharging, and the possibility to work at a low electrolyte support.
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Affiliation(s)
- Michael Biermann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 4, D 38678 Clausthal-Zellerfeld, Germany.
| | - Christian Leppin
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 4, D 38678 Clausthal-Zellerfeld, Germany.
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 4, D 38678 Clausthal-Zellerfeld, Germany.
| | - Thorben Ziemer
- Institute of Electrical Information Technology, Clausthal University of Technology, Leibnizstraße 28, D 38678 Clausthal-Zellerfeld, Germany
| | - Christian Rembe
- Institute of Electrical Information Technology, Clausthal University of Technology, Leibnizstraße 28, D 38678 Clausthal-Zellerfeld, Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 4, D 38678 Clausthal-Zellerfeld, Germany.
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Johannsmann D, Langhoff A, Leppin C, Reviakine I, Maan AMC. Effect of Noise on Determining Ultrathin-Film Parameters from QCM-D Data with the Viscoelastic Model. Sensors (Basel) 2023; 23:1348. [PMID: 36772387 PMCID: PMC9919223 DOI: 10.3390/s23031348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 06/18/2023]
Abstract
Quartz crystal microbalance with dissipation monitoring (QCM-D) is a well-established technique for studying soft films. It can provide gravimetric as well as nongravimetric information about a film, such as its thickness and mechanical properties. The interpretation of sets of overtone-normalized frequency shifts, ∆f/n, and overtone-normalized shifts in half-bandwidth, ΔΓ/n, provided by QCM-D relies on a model that, in general, contains five independent parameters that are needed to describe film thickness and frequency-dependent viscoelastic properties. Here, we examine how noise inherent in experimental data affects the determination of these parameters. There are certain conditions where noise prevents the reliable determination of film thickness and the loss tangent. On the other hand, we show that there are conditions where it is possible to determine all five parameters. We relate these conditions to the mathematical properties of the model in terms of simple conceptual diagrams that can help users understand the model's behavior. Finally, we present new open source software for QCM-D data analysis written in Python, PyQTM.
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Affiliation(s)
- Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße. 4, D-38678 Clausthal-Zellerfeld, Germany
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße. 4, D-38678 Clausthal-Zellerfeld, Germany
| | - Christian Leppin
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße. 4, D-38678 Clausthal-Zellerfeld, Germany
| | - Ilya Reviakine
- Advanced Wave Sensors S.L., Táctica Business Park, Algepsers Street, 24-1, 46988 Paterna Valencia, Spain
- Department of Bioengineering, University of Washington, Seattle, WA 98195-5061, USA
- Institute of Molecular Biology and Biotechnology (IMBB), 70013 Heraklion, Greece
| | - Anna M. C. Maan
- Polymer Science, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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Leppin C, Langhoff A, Johannsmann D. Square-Wave Electrogravimetry Combined with Voltammetry Reveals Reversible Submonolayer Adsorption of Redox-Active Ions. Anal Chem 2022; 94:10227-10233. [PMID: 35802635 DOI: 10.1021/acs.analchem.2c01763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Square-wave voltammetry on electrolytes containing reversible redox pairs in solution was complemented by acoustic microgravimetry, where multifrequency lock-in amplification provides for a time resolution of 2.5 ms and a frequency resolution after accumulation of 12 mHz. The instrument operates similar to a quartz crystal microbalance with dissipation monitoring (QCM-D). The use of square-waves rather than linear ramps makes the analysis more transparent because it reduces the contribution of non-Faraday currents. Also, square-wave electrogravimetry determines the rates of mass transfer with much better sensitivity than its counterpart based on linear voltage ramps. The shifts of frequency and bandwidth are in agreement with the Sauerbrey prediction, meaning that the overtone-normalized frequency shifts, Δf/n, are similar on the different overtones and that the shifts in half bandwidth, ΔΓ, are smaller than the shifts in frequency. Small deviations from the Sauerbrey prediction presumably result from the softness of the adsorbed layer. Because the response time of the QCM signals is much longer than the RC time of double layer recharging as determined with electrochemical impedance spectroscopy (EIS), interpretation in terms of adsorption and desorption is more plausible than interpretation in terms of changed viscosity in the diffuse double layer. Ions of methyl viologen (MV) were found to adsorb to the electrode surface more strongly in the state with a single charge than in the fully oxidized state carrying two charges. The difference in apparent thickness between the oxidized and the reduced state was up to 2 nm, depending on concentration. The gravimetric results obtained on flavin adenine dinucleotide (FAD) depended on pH. At neutral pH, adsorption was largest close to the redox potential. Presumably, the adsorbed molecules are semiquinones, that is, are the intermediates of the underlying two-electron process.
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Affiliation(s)
- Christian Leppin
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Street 4, 38678 Clausthal-Zellerfeld, Germany
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Street 4, 38678 Clausthal-Zellerfeld, Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Street 4, 38678 Clausthal-Zellerfeld, Germany
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Böttcher A, Petri J, Langhoff A, Scholl S, Augustin W, Hohlen A, Johannsmann D. Fouling Pathways in Emulsion Polymerization Differentiated with a Quartz Crystal Microbalance (QCM) Integrated into the Reactor Wall. MACROMOL REACT ENG 2022. [DOI: 10.1002/mren.202100045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Andreas Böttcher
- Institute of Physical Chemistry Clausthal University of Technology Arnold‐Sommerfeld‐Str. 4 38678 Clausthal‐Zellerfeld Germany
| | - Judith Petri
- Institute of Physical Chemistry Clausthal University of Technology Arnold‐Sommerfeld‐Str. 4 38678 Clausthal‐Zellerfeld Germany
| | - Arne Langhoff
- Institute of Physical Chemistry Clausthal University of Technology Arnold‐Sommerfeld‐Str. 4 38678 Clausthal‐Zellerfeld Germany
| | - Stephan Scholl
- Institute of Chemical and Thermal Process Engineering Technische Universität Braunschweig Langer Kamp 7 38106 Braunschweig Germany
| | - Wolfgang Augustin
- Institute of Chemical and Thermal Process Engineering Technische Universität Braunschweig Langer Kamp 7 38106 Braunschweig Germany
| | - Annika Hohlen
- Institute of Chemical and Thermal Process Engineering Technische Universität Braunschweig Langer Kamp 7 38106 Braunschweig Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry Clausthal University of Technology Arnold‐Sommerfeld‐Str. 4 38678 Clausthal‐Zellerfeld Germany
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Affiliation(s)
- Christian Leppin
- Institute of Physical Chemistry Clausthal University of Technology Arnold-Sommerfeld-Str. 4 38678 Clausthal-Zellerfeld Germany
| | - Arne Langhoff
- Institute of Physical Chemistry Clausthal University of Technology Arnold-Sommerfeld-Str. 4 38678 Clausthal-Zellerfeld Germany
| | - Oliver Höfft
- Institute of Electrochemistry Clausthal University of Technology Arnold-Sommerfeld-Str. 6 38678 Clausthal-Zellerfeld Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry Clausthal University of Technology Arnold-Sommerfeld-Str. 4 38678 Clausthal-Zellerfeld Germany
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Leppin C, Langhoff A, Poggemann HF, Gödde AS, Johannsmann D. Fast and slow EQCM response of zwitterionic weak electrolytes to changes in the electrode potential: a pH-mediated mechanism. Analyst 2021; 146:6005-6013. [PMID: 34505583 DOI: 10.1039/d1an01306h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using a fast electrochemical quartz crystal microbalance (EQCM), zwitterionic electrolytes were studied with regard to changes of resonance frequency and resonance bandwidth after the electrode potential was switched. In addition to a fast change of frequency (within milliseconds), a further, slower process with opposite direction is observed. Both the fast and the slow process change sign when the pH is varied across the isoelectric point (pI). The fast process can be attributed to double layer recharging. Its characteristic time is slightly larger than the charge response time (the RC-time) as inferred from electrochemical impedance spectroscopy (EIS). With regard to the slow process, amino acids with moderate concentration behave markedly different from concentrated solutions of proteins. For amino acids, the slow process is larger in amplitude than the fast process and the QCM response is Sauerbrey-like. The shift in half bandwidth is smaller than the shift in frequency and the overtone-normalized frequency shifts agree between overtones (-Δf/n ≈ const. with n the overtone order). This can be explained with a viscosity change in the diffuse double layer. Independent measurements show that the viscosities of these electrolytes are higher than the average in a pH range around the pI. Presumably, the slow process reflects a rearrangement of molecules after the net charge on the molecule has increased or decreased, changing the degree of dipolar coupling and, in consequence, the viscosity. For concentrated solutions of bovine serum albumin (BSA), the QCM response does not follow Sauerbrey behaviour, which can be explained with viscoelasticity and viscoelastic dispersion. The slow process lets the frequency and the bandwidth relax towards a baseline, which is the same for jumps to more positive and to more negative potentials. Presumably, the slow process in this case is caused by a reorientation of molecules inside the Helmholtz layer, such that they screen the electric field more efficiently than immediately after the voltage jump.
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Affiliation(s)
- Christian Leppin
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, 38678 Clausthal-Zellerfeld, Germany.
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, 38678 Clausthal-Zellerfeld, Germany.
| | - Hanna-Friederike Poggemann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, 38678 Clausthal-Zellerfeld, Germany.
| | - Alexander Simon Gödde
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, 38678 Clausthal-Zellerfeld, Germany. .,Institute of Electrochemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 6, 38678 Clausthal-Zellerfeld, Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, 38678 Clausthal-Zellerfeld, Germany.
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Gopalakrishna S, Langhoff A, Brenner G, Johannsmann D. Soft Viscoelastic Particles in Contact with a Quartz Crystal Microbalance (QCM): A Frequency-Domain Lattice Boltzmann Simulation. Anal Chem 2021; 93:10229-10235. [PMID: 34270892 DOI: 10.1021/acs.analchem.1c01612] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Shifts of frequency and bandwidth of a quartz crystal microbalance (QCM) in contact with a structured, viscoelastic sample have been computed with a linearized version of the lattice Boltzmann method (LBM). The algorithm operates in the frequency domain and covers viscoelasticity. The different domains are characterized by different values of the complex viscosity, η, equivalent to different values of the shear modulus, G. Stiff particles are given large |ηSph|, where |ηSph| must be less than ∼100 ηbulk with ηbulk the viscosity of the ambient liquid. Critical to the computational efficiency is a match of the LBM populations at the upper boundary of the simulation box to an analytical solution of the Stokes equation in the bulk above the box. The application example is a test of the ΔΓ/(-Δf)-extrapolation scheme, where Δf and ΔΓ are the shifts in resonance frequency and half bandwidth, respectively. For adsorbed particles, plots of ΔΓ/(-Δf) versus - Δf/n (with n the overtone order) show almost straight lines. The extrapolation of these lines to zero yields a frequency shift, which, after conversion to a thickness with the Sauerbrey equation, closely agrees with the height of the particles. Plots of Δf/n and ΔΓ/n versus n look similar to the corresponding plots obtained for viscoelastic films, where the parameters, which would usually be extracted from those plots (apparent mass and apparent compliance), depend on the geometry and the sample's viscoelasticity in a nontrivial way.
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Affiliation(s)
- Sunil Gopalakrishna
- Institute of Physical Chemistry, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany
| | - Gunther Brenner
- Institute of Applied Mechanics, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany
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Johannsmann D, Langhoff A, Leppin C. Studying Soft Interfaces with Shear Waves: Principles and Applications of the Quartz Crystal Microbalance (QCM). Sensors (Basel) 2021; 21:3490. [PMID: 34067761 PMCID: PMC8157064 DOI: 10.3390/s21103490] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/04/2021] [Accepted: 05/08/2021] [Indexed: 02/07/2023]
Abstract
The response of the quartz crystal microbalance (QCM, also: QCM-D for "QCM with Dissipation monitoring") to loading with a diverse set of samples is reviewed in a consistent frame. After a brief introduction to the advanced QCMs, the governing equation (the small-load approximation) is derived. Planar films and adsorbates are modeled based on the acoustic multilayer formalism. In liquid environments, viscoelastic spectroscopy and high-frequency rheology are possible, even on layers with a thickness in the monolayer range. For particulate samples, the contact stiffness can be derived. Because the stress at the contact is large, the force is not always proportional to the displacement. Nonlinear effects are observed, leading to a dependence of the resonance frequency and the resonance bandwidth on the amplitude of oscillation. Partial slip, in particular, can be studied in detail. Advanced topics include structured samples and the extension of the small-load approximation to its tensorial version.
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Affiliation(s)
- Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 4, 38678 Clausthal-Zellerfeld, Germany
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 4, 38678 Clausthal-Zellerfeld, Germany
| | - Christian Leppin
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 4, 38678 Clausthal-Zellerfeld, Germany
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Leppin C, Peschel A, Meyer FS, Langhoff A, Johannsmann D. Kinetics of viscoelasticity in the electric double layer following steps in the electrode potential studied by a fast electrochemical quartz crystal microbalance (EQCM). Analyst 2021; 146:2160-2171. [DOI: 10.1039/d0an01965h] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A fast EQCM measures the kinetics of the viscosity changes inside the double layer following voltage jumps.
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Affiliation(s)
- Christian Leppin
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
| | - Astrid Peschel
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
| | - Frederick Sebastian Meyer
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
| | - Arne Langhoff
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
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Leppin C, Hampel S, Meyer FS, Langhoff A, Fittschen UEA, Johannsmann D. A Quartz Crystal Microbalance, Which Tracks Four Overtones in Parallel with a Time Resolution of 10 Milliseconds: Application to Inkjet Printing. Sensors (Basel) 2020; 20:E5915. [PMID: 33092072 PMCID: PMC7589769 DOI: 10.3390/s20205915] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/12/2020] [Accepted: 10/15/2020] [Indexed: 01/26/2023]
Abstract
A quartz crystal microbalance (QCM) is described, which simultaneously determines resonance frequency and bandwidth on four different overtones. The time resolution is 10 milliseconds. This fast, multi-overtone QCM is based on multi-frequency lockin amplification. Synchronous interrogation of overtones is needed, when the sample changes quickly and when information on the sample is to be extracted from the comparison between overtones. The application example is thermal inkjet-printing. At impact, the resonance frequencies change over a time shorter than 10 milliseconds. There is a further increase in the contact area, evidenced by an increasing common prefactor to the shifts in frequency, Δf, and half-bandwidth, ΔΓ. The ratio ΔΓ/(-Δf), which quantifies the energy dissipated per time and unit area, decreases with time. Often, there is a fast initial decrease, lasting for about 100 milliseconds, followed by a slower decrease, persisting over the entire drying time (a few seconds). Fitting the overtone dependence of Δf(n) and ΔΓ(n) with power laws, one finds power-law exponents of about 1/2, characteristic of semi-infinite Newtonian liquids. The power-law exponents corresponding to Δf(n) slightly increase with time. The decrease of ΔΓ/(-Δf) and the increase of the exponents are explained by evaporation and formation of a solid film at the resonator surface.
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Affiliation(s)
- Christian Leppin
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (C.L.); (F.S.M.); (A.L.)
| | - Sven Hampel
- Institute of Inorganic and Analytical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (S.H.); (U.E.A.F.)
| | - Frederick Sebastian Meyer
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (C.L.); (F.S.M.); (A.L.)
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (C.L.); (F.S.M.); (A.L.)
| | - Ursula Elisabeth Adriane Fittschen
- Institute of Inorganic and Analytical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (S.H.); (U.E.A.F.)
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (C.L.); (F.S.M.); (A.L.)
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Meyer F, Langhoff A, Arnau A, Johannsmann D, Reviakine I. An ultrafast quartz crystal microbalance based on a frequency comb approach delivers sub-millisecond time resolution. Rev Sci Instrum 2019; 90:115108. [PMID: 31779439 DOI: 10.1063/1.5115979] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 10/15/2019] [Indexed: 06/10/2023]
Abstract
Quartz crystal microbalance with dissipation monitoring (QCMD) is a simple and versatile sensing technique with applications in a wide variety of academic and industrial fields, most notably electrochemistry, biophysics, quality control, and environmental monitoring. QCMD is limited by a relatively poor time resolution, which is of the order of seconds with conventional instrument designs at the noise level usually required. In this work, we present a design of an ultrafast QCMD with submillisecond time resolution. It is based on a frequency comb approach applied to a high-fundamental-frequency (HFF) resonator through a multifrequency lock-in amplifier. The combination allows us to reach data acquisition rates >10 kHz. We illustrate the method using a toy model of a glass sphere dropped on the resonator surfaces, bare or coated with liposomes, in liquid. We discuss some interesting features of the results obtained with the dropped spheres, such as bending of the HFF resonators due to the impact, sphere bouncing (or the absence of it), and contact aging.
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Affiliation(s)
- Frederick Meyer
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Antonio Arnau
- Advanced Wave Sensors S.L., Calle Algepsers 24-1, 46988 Paterna, Valencia, Spain
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Ilya Reviakine
- Advanced Wave Sensors S.L., Calle Algepsers 24-1, 46988 Paterna, Valencia, Spain
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Talewar SK, Halukeerthi SO, Riedlaicher R, Shephard JJ, Clout AE, Rosu-Finsen A, Williams GR, Langhoff A, Johannsmann D, Salzmann CG. Gaseous "nanoprobes" for detecting gas-trapping environments in macroscopic films of vapor-deposited amorphous ice. J Chem Phys 2019; 151:134505. [PMID: 31594355 DOI: 10.1063/1.5113505] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vapor-deposited amorphous ice, traditionally called amorphous solid water (ASW), is one of the most abundant materials in the universe and a prototypical material for studying physical vapor-deposition processes. Its complex nature arises from a strong tendency to form porous structures combined with complicated glass transition, relaxation, and desorption behavior. To gain further insights into the various gas-trapping environments that exist in ASW and hence its morphology, films in the 25-100 μm thickness range were codeposited with small amounts of gaseous "nanoprobes" including argon, methane, helium, and carbon dioxide. Upon heating in the 95-185 K temperature range, three distinct desorption processes are observed which we attribute to the gas desorption out of open cracks above 100 K, from internal voids that collapse due to the glass transition at ∼125 K and finally from fully matrix-isolated gas induced by the irreversible crystallization to stacking disordered ice (ice Isd) at ∼155 K. Nanoscale films of ASW have only displayed the latter desorption process which means that the first two desorption processes arise from the macroscopic dimensions of our ASW films. Baffling the flow of water vapor toward the deposition plate greatly reduces the first desorption feature, and hence the formation of cracks, but it significantly increases the amount of matrix-isolated gas. The complex nature in which ASW can trap gaseous species is thought to be relevant for a range of cosmological processes.
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Affiliation(s)
- Sukhpreet K Talewar
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Siriney O Halukeerthi
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Regina Riedlaicher
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Jacob J Shephard
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Alexander E Clout
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Alexander Rosu-Finsen
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Gareth R Williams
- UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, Clausthal-Zellerfeld, Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, Clausthal-Zellerfeld, Germany
| | - Christoph G Salzmann
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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Peschel A, Langhoff A, Uhl E, Dathathreyan A, Haindl S, Johannsmann D, Reviakine I. Lipid phase behavior studied with a quartz crystal microbalance: A technique for biophysical studies with applications in screening. J Chem Phys 2017; 145:204904. [PMID: 27908120 DOI: 10.1063/1.4968215] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Quartz crystal microbalance (QCM) is emerging as a versatile tool for studying lipid phase behavior. The technique is attractive for fundamental biophysical studies as well applications because of its simplicity, flexibility, and ability to work with very small amounts of material crucial for biomedical studies. Further progress hinges on the understanding of the mechanism, by which a surface-acoustic technique such as QCM, senses lipid phase changes. Here, we use a custom-built instrument with improved sensitivity to investigate phase behavior in solid-supported lipid systems of different geometries (adsorbed liposomes and bilayers). We show that we can detect a model anesthetic (ethanol) through its effect on the lipid phase behavior. Further, through the analysis of the overtone dependence of the phase transition parameters, we show that hydrodynamic effects are important in the case of adsorbed liposomes, and viscoelasticity is significant in supported bilayers, while layer thickness changes make up the strongest contribution in both systems.
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Affiliation(s)
- Astrid Peschel
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Eva Uhl
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Aruna Dathathreyan
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Susanne Haindl
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
| | - Ilya Reviakine
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Petri J, Hochstädt S, Nentwig T, Pausch A, Langhoff A, Johannsmann D. A Fast Electrochemical Quartz Crystal Microbalance,which Acquires Frequency and Bandwidth on Multiple Overtones. ELECTROANAL 2016. [DOI: 10.1002/elan.201600580] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Judith Petri
- Institute of Physical Chemistry; Clausthal University of Technology; 38678 Clausthal-Zellerfeld Germany
| | - Sebastian Hochstädt
- Institute of Physical Chemistry; Clausthal University of Technology; 38678 Clausthal-Zellerfeld Germany
| | - Tristan Nentwig
- Institute of Physical Chemistry; Clausthal University of Technology; 38678 Clausthal-Zellerfeld Germany
| | - Ansgar Pausch
- Institute of Physical Chemistry; Clausthal University of Technology; 38678 Clausthal-Zellerfeld Germany
| | - Arne Langhoff
- Institute of Physical Chemistry; Clausthal University of Technology; 38678 Clausthal-Zellerfeld Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry; Clausthal University of Technology; 38678 Clausthal-Zellerfeld Germany
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Peschel A, Böttcher A, Langhoff A, Johannsmann D. Probing the electrical impedance of thin films on a quartz crystal microbalance (QCM), making use of frequency shifts and piezoelectric stiffening. Rev Sci Instrum 2016; 87:115002. [PMID: 27910637 DOI: 10.1063/1.4966247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using a temperature-responsive polymer film as an example, it was shown that a conventional quartz crystal microbalance (QCM) can probe a sample's electrical properties in addition to its thickness and softness. The film's electrical impedance was accessed by alternating between the driving voltage being applied to the front electrode and the back electrode. The opposing electrode was grounded in both cases. In the first configuration, the electrical properties of the sample do have an influence on the resonance frequency because of piezoelectric stiffening. In the second, they do not. Using this scheme, it was monitored how the electrical impedance of a film composed of a mixture of poly-N-isopropylacrylamide and polyvinylalcohol changes when the film swells and deswells.
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Affiliation(s)
- Astrid Peschel
- Institute of Physical Chemistry, Clausthal University of Technology, Clausthal-Zellerfeld 38678, Germany
| | - Andreas Böttcher
- Institute of Physical Chemistry, Clausthal University of Technology, Clausthal-Zellerfeld 38678, Germany
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Clausthal-Zellerfeld 38678, Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, Clausthal-Zellerfeld 38678, Germany
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Peschel A, Langhoff A, Johannsmann D. Coupled resonances allow studying the aging of adhesive contacts between a QCM surface and single, micrometer-sized particles. Nanotechnology 2015; 26:484001. [PMID: 26552744 DOI: 10.1088/0957-4484/26/48/484001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Interparticle contacts and contacts between particles and surfaces are known to change over time. The contact area, the contact stiffness, and the contact strength usually increase as the contact ages. Contact aging is mostly driven by capillary forces, but also by plastic deformation. Making use of acoustic resonators, we have studied the stiffness of contacts between the surface of a quartz crystal microbalance (QCM) and individual, micrometer-sized particles adsorbed to the resonator surface. Studying single particles avoids ensemble-averaging. Central to the analysis is the coupled resonance, occurring when a surface-attached particle together with the link forms a resonator of its own. If the frequency of this second resonator comes close to one of the crystal's overtones, plots of shifts in resonance bandwidth versus overtone order display a resonance curve. This secondary resonance is caused by the coupling between the particle's resonance and the main resonance. One can read the frequency of the coupled resonance from this plot. Similarly, resonance curves are observed in plots of frequency and bandwidth versus time, if the contact stiffness varies smoothly with time. Because the coupled resonance is a characteristic feature, it is easily identified even in cases where frequency shifts of some other origin are superimposed onto the data. For the cases studied here, the links stiffened while they dried. Interestingly, the efficiency of coupling between the particle resonance and the main resonance decreased at the same time. This can be explained with an increase in the link's bending stiffness. The analysis highlights that a QCM experiment amounts to vibrational spectroscopy on surface-attached particles. Among the application examples is the adsorption and drying of a lycopodium spore. Clearly, the technique is also applicable to problems of bioadhesion.
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Affiliation(s)
- Astrid Peschel
- Institute of Physical Chemistry, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany
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König R, Langhoff A, Johannsmann D. Steady flows above a quartz crystal resonator driven at elevated amplitude. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 89:043016. [PMID: 24827341 DOI: 10.1103/physreve.89.043016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Indexed: 06/03/2023]
Abstract
A steady flow of liquid was observed above the surface of a quartz crystal microbalance under conditions where the oscillation amplitude exceeded 10 nm. The streaming flow occurs parallel to the displacement vector and is directed towards the center of the plate. It is expected to have applications in acoustic sensing, in microfluidics, and in micromechanics in a wider sense. The flow is caused by the nonlinear term in the Navier-Stokes equation, which can produce a nonzero time-averaged force from a periodic velocity field. Central to the explanation are the flexural admixtures to the resonator's mode of vibration. Unlike pressure-driven flows, the acoustically driven steady flow attains its maximum velocity at a distance of a few hundred nanometers from the surface. It is therefore efficient in breaking bonds between adsorbed particles and the resonator surface. As a side aspect, the flow pattern amounts to a diagnostic tool, which gives access to the pattern of vibration. In particular, it leads to an estimate of the magnitude of the flexural admixtures to the thickness-shear vibration.
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Affiliation(s)
- Rebekka König
- Institute of Physical Chemistry, Arnold-Sommerfeld-Strasse 4, D-38678 Clausthal-Zellerfeld, Germany
| | - Arne Langhoff
- Institute of Physical Chemistry, Arnold-Sommerfeld-Strasse 4, D-38678 Clausthal-Zellerfeld, Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Arnold-Sommerfeld-Strasse 4, D-38678 Clausthal-Zellerfeld, Germany
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Langhoff A, Johannsmann D. Attractive forces on hard and soft colloidal objects located close to the surface of an acoustic-thickness shear resonator. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 88:013001. [PMID: 23944543 DOI: 10.1103/physreve.88.013001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 04/19/2013] [Indexed: 06/02/2023]
Abstract
Colloidal particles located close to the surface of an acoustic thickness shear resonator feel an attractive steady force, which is induced by the high-frequency tangential motion of the resonator surface. The range of the force is about half the penetration depth of the transverse viscous wave, that is, half of the thickness of the Stokes boundary layer. For an oscillation amplitude of 10 nm and a particle radius of 100 nm, the depth of attractive potential well corresponds to about 3 times the thermal energy, k(B)T. The force therefore suffices to overcome Brownian motion.
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Affiliation(s)
- Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, 38678 Clausthal-Zellerfeld, Germany
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Rossow T, Heyman JA, Ehrlicher AJ, Langhoff A, Weitz DA, Haag R, Seiffert S. Controlled synthesis of cell-laden microgels by radical-free gelation in droplet microfluidics. J Am Chem Soc 2012; 134:4983-9. [PMID: 22356466 DOI: 10.1021/ja300460p] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Micrometer-sized hydrogel particles that contain living cells can be fabricated with exquisite control through the use of droplet-based microfluidics and bioinert polymers such as polyethyleneglycol (PEG) and hyperbranched polyglycerol (hPG). However, in existing techniques, the microgel gelation is often achieved through harmful reactions with free radicals. This is detrimental for the viability of the encapsulated cells. To overcome this limitation, we present a technique that combines droplet microfluidic templating with bio-orthogonal thiol-ene click reactions to fabricate monodisperse, cell-laden microgel particles. The gelation of these microgels is achieved via the nucleophilic Michael addition of dithiolated PEG macro-cross-linkers to acrylated hPG building blocks and does not require any initiator. We systematically vary the microgel properties through the use of PEG linkers with different molecular weights along with different concentrations of macromonomers to investigate the influence of these parameters on the viability and proliferation of encapsulated yeast cells. We also demonstrate the encapsulation of mammalian cells including fibroblasts and lymphoblasts.
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Affiliation(s)
- Torsten Rossow
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Takustr. 3, D-14195 Berlin, Germany
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Nikiforow I, Adams J, König AM, Langhoff A, Pohl K, Turshatov A, Johannsmann D. Self-stratification during film formation from latex blends driven by differences in collective diffusivity. Langmuir 2010; 26:13162-13167. [PMID: 20695554 DOI: 10.1021/la101697r] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Coatings with vertical gradients in composition were produced by drying an aqueous polymer dispersion containing both charged and neutral particles. After drying, the neutral component was enriched at the film/air interface. The spontaneous vertical segregation between the two types of particles goes back to a difference in collective diffusivity. As the film dries, a layer enriched in polymer develops at the top. Due to their mutual repulsion, charged spheres escape from this layer more quickly than their neutral counterparts. Provided that the total time of drying is between the times of diffusion for the two types of particles (approximately H(0)(2)/D(c) with H(0) the initial film thickness and D(c) the collective diffusivity of the respective species), a concentration gradient persists after the film has turned dry. This effect can be used to create a functionally graded material (FGM) in a single coating step.
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Affiliation(s)
- Irina Nikiforow
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany
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Burkhardt O, Hafer C, Langhoff A, Kaever V, Kumar V, Welte T, Haller H, Fliser D, Kielstein JT. Pharmacokinetics of ertapenem in critically ill patients with acute renal failure undergoing extended daily dialysis. Nephrol Dial Transplant 2008; 24:267-71. [DOI: 10.1093/ndt/gfn472] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Langhoff A, Giesselmann F. Kinetics of the photoferroelectric effect in chiral smectic-C liquid crystals studied by time-resolved measurements of spontaneous electric polarization and director tilt angle. Chemphyschem 2002; 3:424-32. [PMID: 12465502 DOI: 10.1002/1439-7641(20020517)3:5<424::aid-cphc424>3.0.co;2-o] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The origin of the photoferroelectric effect in liquid crystals, where the spontaneous polarization of a chiral ferroelectric smectic-C* (SmC*) host phase is changed by the E,Z-photoisomerization of azobenzene dopant molecules, was investigated by kinetic studies on the molecular isomerization and the subsequent changes in the SmC* order parameters, the director tilt angle, and the spontaneous electric polarization. The photoresponse of a liquid-crystal mixture consisting of 5 mol% 4,4'-bis-[(2-methyl)butyloxy]azobenzene dissolved in the SmC* host phase FLC 6430 was studied at low UV-light intensities (lambda = 366 nm, 15 microW cm-2) using an electrooptical technique that measured the desired parameters with a time resolution of about 1 s. The time-resolved measurements of optical absorption, tilt angle, and spontaneous polarization during the thermal reisomerization after ending the sample irradiation showed that the photoinduced changes in the spontaneous polarization simultaneously followed the molecular isomerization with the same rate constant and activation energy, while the director tilt angle remained basically unchanged. Minor changes in the tilt are explained by the local heating of the sample due to the optical absorption. Since the photoinduced change in polarization was observed at constant tilt, we conclude that in the limit of low UV intensity the photoferroelectric effect originates from a photo-induced change of the bilinear coupling coefficient between the polarization and the tilt. In the molecular theory of chiral SmC* liquid crystals, the coupling coefficient is related to the bias of molecular rotations. This bias may be considerably disturbed by the formation of the bent Z-isomers during the photoisomerization.
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Affiliation(s)
- Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Strasse 4 38678 Clausthal-Zellerfeld, Germany
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Bowe B, Martin S, Toal V, Langhoff A, Whelan M. Dual in-plane electronic speckle pattern interferometry system with electro-optical switching and phase shifting. Appl Opt 1999; 38:666-673. [PMID: 18305661 DOI: 10.1364/ao.38.000666] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A dual in-plane electronic speckle pattern interferometry (ESPI) system has been developed for in situ measurements. The optical setup is described here. The system uses an electro-optical switch to change between the illumination directions for x and y sensitivity. The ability of the electro-optic device to change the polarization of the laser light forms the basis of this switch. The electro-optic device is a liquid-crystal layer cemented between two optically flat glass plates. An electric field can be set up across the layer by application of a voltage to electrodes. The speckle interferometry system incorporates two additional liquid-crystal devices to facilitate phase shifting, and the overall system is controlled by advanced software, which allows switching between the two perpendicular planes in quasi real time. The fact that there are no moving parts is an advantage in any ESPI system for which mechanical stability is vital.
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Affiliation(s)
- B Bowe
- Centre for Industrial and Engineering Optics, School of Physics, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland
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Lunkwitz R, Tschierske C, Langhoff A, Gießelmann F, Zugenmaier P. Axial chiral allenylacetates as novel ferroelectric liquid crystals. ACTA ACUST UNITED AC 1997. [DOI: 10.1039/a701032j] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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