Symmetry

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3 pages, 169 KiB

Open AccessEditorial

Special Issue of Symmetry: “Recent Advances in Linear and Nonlinear Optics”

by Thomas Noblet and Christophe Humbert

Symmetry 2022, 14(3), 495; https://doi.org/10.3390/sym14030495 - 28 Feb 2022

Viewed by 1592

Abstract

In this Special Issue, invited researchers elaborate on ‘Recent Advances in Linear and Nonlinear Optics’, demonstrating how sensitive light–matter interactions are concerning symmetry [...] Full article

(This article belongs to the Special Issue Recent Advances in Linear and Nonlinear Optics)

Research

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14 pages, 2681 KiB

Open AccessArticle

Density Functional Theory Study of Substitution Effects on the Second-Order Nonlinear Optical Properties of Lindquist-Type Organo-Imido Polyoxometalates

by Emna Rtibi and Benoit Champagne

Symmetry 2021, 13(9), 1636; https://doi.org/10.3390/sym13091636 - 6 Sep 2021

Cited by 9 | Viewed by 2348

Abstract

Density functional theory and time-dependent density functional theory have been enacted to investigate the effects of donor and acceptor on the first hyperpolarizability of Lindquist-type organo-imido polyoxometalates (POMs). These calculations employ a range-separated hybrid exchange-correlation functional (ωB97X-D), account for solvent effects using the [...] Read more.

Density functional theory and time-dependent density functional theory have been enacted to investigate the effects of donor and acceptor on the first hyperpolarizability of Lindquist-type organo-imido polyoxometalates (POMs). These calculations employ a range-separated hybrid exchange-correlation functional (ωB97X-D), account for solvent effects using the implicit polarizable continuum model, and analyze the first hyperpolarizabilities by using the two-state approximation. They highlight the beneficial role of strong donors as well as of π-conjugated spacers (CH=CH rather than C≡C) on the first hyperpolarizabilities. Analysis based on the unit sphere representation confirms the one-dimensional push-pull π-conjugated character of the POMs substituted by donor groups and the corresponding value of the depolarization ratios close to 5. Furthermore, the use of the two-state approximation is demonstrated to be suitable for explaining the origin of the variations of the first hyperpolarizabilities as a function of the characteristics of a unique low-energy charge-transfer excited state and to attribute most of the first hyperpolarizability changes to the difference of dipole moment between the ground and that charge-transfer excited state. Full article

(This article belongs to the Special Issue Recent Advances in Linear and Nonlinear Optics)

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10 pages, 4028 KiB

Open AccessArticle

Spatial Dependence of the Dipolar Interaction between Quantum Dots and Organic Molecules Probed by Two-Color Sum-Frequency Generation Spectroscopy

by Thomas Noblet, Laurent Dreesen, Abderrahmane Tadjeddine and Christophe Humbert

Symmetry 2021, 13(2), 294; https://doi.org/10.3390/sym13020294 - 9 Feb 2021

Cited by 3 | Viewed by 2104

Abstract

Given the tunability of their optical properties over the UV–Visible–Near IR spectral range, ligand-capped quantum dots (QDs) are employed for the design of optical biosensors with low detection threshold. Thanks to non-linear optical spectroscopies, the absorption properties of QDs are indeed used to [...] Read more.

Given the tunability of their optical properties over the UV–Visible–Near IR spectral range, ligand-capped quantum dots (QDs) are employed for the design of optical biosensors with low detection threshold. Thanks to non-linear optical spectroscopies, the absorption properties of QDs are indeed used to selectively enhance the local vibrational response of molecules located in their vicinity. Previous studies led to assume the existence of a vibroelectronic QD–molecule coupling based on dipolar interaction. However, no systematic study on the strength of this coupling has been performed to date. In order to address this issue, we use non-linear optical Two-Color Sum-Frequency Generation (2C-SFG) spectroscopy to probe thick QD layers deposited on calcium fluoride (CaF

_{2}

) prisms previously functionalized by a self-assembled monolayer of phenyltriethoxysilane (PhTES) molecules. Here, 2C-SFG is performed in Attenuated Total Reflection (ATR) configuration. By comparing the molecular vibrational enhancement measured for QD–ligand coupling and QD–PhTES coupling, we show that the spatial dependence of the QD–molecule interactions (∼1/r

^{3}

, with r the QD–molecule distance) is in agreement with the hypothesis of a dipole–dipole interaction. Full article

(This article belongs to the Special Issue Recent Advances in Linear and Nonlinear Optics)

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13 pages, 1560 KiB

Open AccessArticle

Second Harmonic Scattering of Molecular Aggregates

by Guillaume Revillod, Julien Duboisset, Isabelle Russier-Antoine, Emmanuel Benichou, Christian Jonin and Pierre-François Brevet

Symmetry 2021, 13(2), 206; https://doi.org/10.3390/sym13020206 - 27 Jan 2021

Cited by 6 | Viewed by 1956

Abstract

A general model is developed to describe the polarization-resolved second harmonic scattering (SHS) response from a liquid solution of molecular aggregates. In particular, the molecular spatial order is introduced to consider the coherent contribution, also known as the retarded contribution, besides the incoherent [...] Read more.

A general model is developed to describe the polarization-resolved second harmonic scattering (SHS) response from a liquid solution of molecular aggregates. In particular, the molecular spatial order is introduced to consider the coherent contribution, also known as the retarded contribution, besides the incoherent contribution. The model is based on the description of a liquid suspension of molecular dyes represented by point-like nonlinear dipoles, locally excited by the fundamental field and radiating at the harmonic frequency. It is shown that for a non-centrosymmetrical spatial arrangement of the nonlinear dipoles, the SHS response is very similar to the purely incoherent response, and is of electric dipole origin. However, for centrosymmetrical or close to centrosymmetrical spatial arrangements of the nonlinear dipoles, the near cancellation of the incoherent contribution due to the inversion symmetry rule allows the observation of the coherent contribution of the SHS response, also known as the electric quadrupole contribution. This model is illustrated with experimental data obtained for aqueous solutions of the dye Crystal Violet (CV) in the presence of sodium dodecyl sulfate (SDS) and mixed water-methanol solutions of the dye 4-(4–dihexadecylaminostyryl)-N-methylpyridinium iodide (DiA), a cationic amphiphilic probe molecule with a strong first hyper-polarizability; both CV and DiA form molecular aggregates in these conditions. The quantitative determination of a retardation parameter opens a window into the spatial arrangements of the dyes in the aggregates, despite the small nanoscale dimensions of the latter. Full article

(This article belongs to the Special Issue Recent Advances in Linear and Nonlinear Optics)

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16 pages, 2554 KiB

Open AccessArticle

Assessing the Molecular Specificity and Orientation Sensitivity of Infrared, Raman, and Vibrational Sum-Frequency Spectra

by Fei Chen, Lea Gozdzialski, Kuo-Kai Hung, Ulrike Stege and Dennis K. Hore

Symmetry 2021, 13(1), 42; https://doi.org/10.3390/sym13010042 - 30 Dec 2020

Cited by 3 | Viewed by 2500

Abstract

Linear programming was used to assess the ability of polarized infrared absorption, Raman scattering, and visible–infrared sum-frequency generation to correctly identify the composition of a mixture of molecules adsorbed onto a surface in four scenarios. The first two scenarios consisted of a distribution [...] Read more.

Linear programming was used to assess the ability of polarized infrared absorption, Raman scattering, and visible–infrared sum-frequency generation to correctly identify the composition of a mixture of molecules adsorbed onto a surface in four scenarios. The first two scenarios consisted of a distribution of species where the polarity of the orientation distribution is known, both with and without consideration of an arbitrary scaling factor between candidate spectra and the observed spectra of the mixture. The final two scenarios have repeated the tests, but assuming that the polarity of the orientation is unknown, so the symmetry-breaking attributes of the second-order nonlinear technique are required. The results indicate that polarized Raman spectra are more sensitive to orientation and molecular identity than the other techniques. However, further analysis reveals that this sensitivity is not due to the high-order angle dependence of Raman, but is instead attributed to the number of unique projections that can be measured in a polarized Raman experiment. Full article

(This article belongs to the Special Issue Recent Advances in Linear and Nonlinear Optics)

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Review

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26 pages, 5114 KiB

Open AccessReview

A Unified Mathematical Formalism for First to Third Order Dielectric Response of Matter: Application to Surface-Specific Two-Colour Vibrational Optical Spectroscopy

by Christophe Humbert and Thomas Noblet

Symmetry 2021, 13(1), 153; https://doi.org/10.3390/sym13010153 - 19 Jan 2021

Cited by 6 | Viewed by 3256

Abstract

To take advantage of the singular properties of matter, as well as to characterize it, we need to interact with it. The role of optical spectroscopies is to enable us to demonstrate the existence of physical objects by observing their response to light [...] Read more.

To take advantage of the singular properties of matter, as well as to characterize it, we need to interact with it. The role of optical spectroscopies is to enable us to demonstrate the existence of physical objects by observing their response to light excitation. The ability of spectroscopy to reveal the structure and properties of matter then relies on mathematical functions called optical (or dielectric) response functions. Technically, these are tensor Green’s functions, and not scalar functions. The complexity of this tensor formalism sometimes leads to confusion within some articles and books. Here, we do clarify this formalism by introducing the physical foundations of linear and non-linear spectroscopies as simple and rigorous as possible. We dwell on both the mathematical and experimental aspects, examining extinction, infrared, Raman and sum-frequency generation spectroscopies. In this review, we thus give a personal presentation with the aim of offering the reader a coherent vision of linear and non-linear optics, and to remove the ambiguities that we have encountered in reference books and articles. Full article

(This article belongs to the Special Issue Recent Advances in Linear and Nonlinear Optics)

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57 pages, 12960 KiB

Open AccessReview

Characterisation and Manipulation of Polarisation Response in Plasmonic and Magneto-Plasmonic Nanostructures and Metamaterials

by Pritam Khan, Grace Brennan, James Lillis, Syed A. M. Tofail, Ning Liu and Christophe Silien

Symmetry 2020, 12(8), 1365; https://doi.org/10.3390/sym12081365 - 17 Aug 2020

Cited by 16 | Viewed by 5842

Abstract

Optical properties of metal nanostructures, governed by the so-called localised surface plasmon resonance (LSPR) effects, have invoked intensive investigations in recent times owing to their fundamental nature and potential applications. LSPR scattering from metal nanostructures is expected to show the symmetry of the [...] Read more.

Optical properties of metal nanostructures, governed by the so-called localised surface plasmon resonance (LSPR) effects, have invoked intensive investigations in recent times owing to their fundamental nature and potential applications. LSPR scattering from metal nanostructures is expected to show the symmetry of the oscillation mode and the particle shape. Therefore, information on the polarisation properties of the LSPR scattering is crucial for identifying different oscillation modes within one particle and to distinguish differently shaped particles within one sample. On the contrary, the polarisation state of light itself can be arbitrarily manipulated by the inverse designed sample, known as metamaterials. Apart from polarisation state, external stimulus, e.g., magnetic field also controls the LSPR scattering from plasmonic nanostructures, giving rise to a new field of magneto-plasmonics. In this review, we pay special attention to polarisation and its effect in three contrasting aspects. First, tailoring between LSPR scattering and symmetry of plasmonic nanostructures, secondly, manipulating polarisation state through metamaterials and lastly, polarisation modulation in magneto-plasmonics. Finally, we will review recent progress in applications of plasmonic and magneto-plasmonic nanostructures and metamaterials in various fields. Full article

(This article belongs to the Special Issue Recent Advances in Linear and Nonlinear Optics)

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16 pages, 2979 KiB

Open AccessFeature PaperReview

Applications of Symmetry Breaking in Plasmonics

by Grégory Barbillon, Andrey Ivanov and Andrey K. Sarychev

Symmetry 2020, 12(6), 896; https://doi.org/10.3390/sym12060896 - 1 Jun 2020

Cited by 24 | Viewed by 4384

Abstract

Plasmonics is one of the most used domains for applications to optical devices, biological and chemical sensing, and non-linear optics, for instance. Indeed, plasmonics enables confining the electromagnetic field at the nanoscale. The resonances of plasmonic systems can be set in a given [...] Read more.

Plasmonics is one of the most used domains for applications to optical devices, biological and chemical sensing, and non-linear optics, for instance. Indeed, plasmonics enables confining the electromagnetic field at the nanoscale. The resonances of plasmonic systems can be set in a given domain of a spectrum by adjusting the geometry, the spatial arrangement, and the nature of the materials. Moreover, symmetry breaking can be used for the further improvement of the optical properties of the plasmonic systems. In the last three years, great advances in or insights into the use of symmetry breaking in plasmonics have occurred. In this mini-review, we present recent insights and advances on the use of symmetry breaking in plasmonics for applications to chemistry, sensing, devices, non-linear optics, and chirality. Full article

(This article belongs to the Special Issue Recent Advances in Linear and Nonlinear Optics)

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