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Novelli F. Terahertz spectroscopy of thick and diluted water solutions. OPTICS EXPRESS 2024; 32:11041-11056. [PMID: 38570962 DOI: 10.1364/oe.510393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 01/16/2024] [Indexed: 04/05/2024]
Abstract
While bright terahertz sources are used to perform nonlinear experiments, they can be advantageous for high-precision linear measurements of opaque samples. By placing the sample away from the focus, nonlinearities can be suppressed, and sizeable amounts of transmitted radiation detected. Here, this approach is demonstrated for a 0.5 mm thick layer of liquid water in a static sample holder. Variations of the index of refraction as small as (7 ± 2) · 10-4 were detected at 0.58 THz for an aqueous salt solution containing ten millimoles of sodium chloride. To my knowledge, this precision is unprecedented in time-domain spectroscopy studies of diluted aqueous systems or other optically thick and opaque materials.
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Shelton DP. Correlated libration in liquid water. J Chem Phys 2024; 160:114507. [PMID: 38511657 DOI: 10.1063/5.0200094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 03/04/2024] [Indexed: 03/22/2024] Open
Abstract
The libration spectrum of liquid H2O is resolved into an octupolar twisting libration band at 485 cm-1 and dipolar rocking-wagging libration bands at 707 and 743 cm-1 using polarization analysis of the hyper-Raman scattering (HRS) spectrum. Dipole interactions and orientation correlation over distances less than 2 nm account for the 36 cm-1 splitting of the longitudinal and transverse polarized bands of the dipolar rocking-wagging libration mode, while the intensity difference observed for the bands is the result of libration correlation over distances larger than 200 nm. The coupled rock and wag libration in water is similar to libration modes in ice. The libration relaxation time determined from the width of the spectrum is 36-54 fs. Polarization analysis of the HRS spectrum also shows long range correlation for molecular orientation and hindered translation, bending and stretching vibrations in water.
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Affiliation(s)
- David P Shelton
- Department of Physics and Astronomy, University of Nevada, Las Vegas, Nevada 89154-4002, USA
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Ahlmann S, Hoffmann L, Keppler M, Münzner P, Tonauer CM, Loerting T, Gainaru C, Böhmer R. Isotope effects on the dynamics of amorphous ices and aqueous phosphoric acid solutions. Phys Chem Chem Phys 2022; 24:14846-14856. [PMID: 35697341 DOI: 10.1039/d2cp01455f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The glass transitions of amorphous ices as well as of aqueous phosphoric acid solutions were reported to display very large 1H/2H isotope effects. Using dielectric spectroscopy, in both types of glassformers for equimolar protonated/deuterated mixtures an almost ideal isotope-mixing behavior rather than a bimodal relaxation is found. For the amorphous ices this finding is interpreted in terms of a glass-to-liquid rather than an orientational glass transition scenario. Based on calorimetric results revealing that major 16O/18O isotope effects are missing, the latter scenario was previously favored for the amorphous ices. Considering the dielectric results on 18O substituted amorphous ices and by comparison with corresponding results for the aqueous phosphoric acid solutions, it is argued that the present findings are compatible with the glass-to-liquid scenario. To provide additional information regarding the deeply supercooled state of 1H/2H isotopically mixed and 18O substituted glassformers, the aqueous phosphoric acid solutions are studied using shear mechanical spectroscopy as well, a technique which so far could not successfully be applied to characterize the glass transitions of the amorphous ices.
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Affiliation(s)
- S Ahlmann
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - L Hoffmann
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - M Keppler
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - P Münzner
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - C M Tonauer
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - T Loerting
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - C Gainaru
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany.,Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - R Böhmer
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
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Design and Analysis of a Single Humidity Sensor Based on TDLAS for Water Vapor and Heavy Oxygen Water Vapor Detection. PHOTONICS 2022. [DOI: 10.3390/photonics9030175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
In this paper, a single humidity sensor for water vapor and heavy oxygen water vapor detection is presented. The sensor is based on tunable diode laser absorption spectroscopy (TDLAS) and thus has high sensitivity, good selectivity, and a short response time. A 1372 nm distributed feedback (DFB) diode laser is utilized as the light source, the wavelength tuning range of which covers the absorption lines of water vapor and heavy oxygen water vapor. A Herriott gas cell with 12 m optical length is designed for signal-to-noise ratio (SNR) enhancement. The sensor can distinguish between water vapor and heavy oxygen water vapor effectively. The accuracy of water detection is within ±0.5% RH. The accuracy of heavy oxygen water vapor detection is within ±1.0% RH.
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Kringle L, Thornley WA, Kay BD, Kimmel GA. Isotope effects on the structural transformation and relaxation of deeply supercooled water. J Chem Phys 2022; 156:084501. [DOI: 10.1063/5.0078796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We have examined the structure of supercooled liquid D2O as a function of temperature between 185 and 255 K using pulsed laser heating to rapidly heat and cool the sample on a nanosecond timescale. The liquid structure can be represented as a linear combination of two structural motifs, with a transition between them described by a logistic function centered at 218 K with a width of 10 K. The relaxation to a metastable state, which occurred prior to crystallization, exhibited nonexponential kinetics with a rate that was dependent on the initial structural configuration. When the temperature is scaled by the temperature of maximum density, which is an isostructural point of the isotopologues, the structural transition and the non-equilibrium relaxation kinetics of D2O agree remarkably well with those for H2O.
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Affiliation(s)
- Loni Kringle
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA
| | - Wyatt A. Thornley
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA
| | - Bruce D. Kay
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA
| | - Greg A. Kimmel
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA
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Hoffmann L, Beerwerth J, Adjei-Körner M, Fuentes-Landete V, Tonauer CM, Loerting T, Böhmer R. Oxygen NMR of high-density and low-density amorphous ice. J Chem Phys 2022; 156:084503. [DOI: 10.1063/5.0080333] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using oxygen-17 as a nuclear probe, spin relaxometry was applied to study the high-density and low-density states of amorphous ice, covering temperatures below and somewhat above their glass transitions. These findings are put in perspective with results from deuteron nuclear magnetic resonance and with calculations based on dielectrically detected correlation times. This comparison reveals the presence of a wide distribution of correlation times. Furthermore, oxygen-17 central-transition echo spectra were recorded for wide ranges of temperature and pulse spacing. The spectra cannot be described by a single set of quadrupolar parameters, suggesting a distribution of H–O–H opening angles that is broader for high-density than for low-density amorphous ice. Simulations of the pulse separation dependent spin-echo spectra for various scenarios demonstrate that a small-step frequency diffusion process, assigned to the presence of homonuclear oxygen–oxygen interactions, determines the shape evolution of the pulse-separation-dependent spectra.
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Affiliation(s)
- Lars Hoffmann
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - Joachim Beerwerth
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | | | - Violeta Fuentes-Landete
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - Christina M. Tonauer
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - Thomas Loerting
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - Roland Böhmer
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
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Hölzl C, Forbert H, Marx D. Dielectric relaxation of water: assessing the impact of localized modes, translational diffusion, and collective dynamics. Phys Chem Chem Phys 2021; 23:20875-20882. [PMID: 34523631 DOI: 10.1039/d1cp03507j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A multitude of distinct physical processes and molecular mechanisms have been introduced in the past in an effort to understand the unusual dielectric loss spectrum of water with its pronounced peak at roughly 20 GHz. Our computer simulations including ab initio molecular dynamics provide no evidence for a major impact of cage dynamics or local-diffusive motion on the lineshape below 200 GHz. We also show that the collective motion of hundreds of water molecules and/or their significant diffusive displacements are not required. Instead, the dielectric relaxation of water up to about 200 GHz can be quantitatively described in terms of two unimodal and smoothly decaying spectral contributions.
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Affiliation(s)
- Christoph Hölzl
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany.
| | - Harald Forbert
- Center for Solvation Science ZEMOS, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Dominik Marx
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany.
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