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Open AccessFeature PaperEditor’s ChoiceArticle

MCD and Induced CD of a Tetraphenoxyperylene-Based Dye in Chiral Solvents: An Experimental and Computational Study

by Simone Ghidinelli, Marco Fusè, Giuseppe Mazzeo, Sergio Abbate and Giovanna Longhi

Symmetry 2022, 14(6), 1108; https://doi.org/10.3390/sym14061108 - 28 May 2022

Cited by 5 | Viewed by 3227

The magnetic circular dichroism (MCD) spectrum of N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetraphenoxyperylene-3,4:9,10-tetracarboxydiimide, also known as Lumogen Red 300 or ROT-300, has been recorded both in achiral and chiral solvents. The induced CD spectra in chiral solvents have, similarly, been recorded. A discussion of the spectroscopic response, both in CD and in MCD experiments, is presented in this paper. Both types of spectra have been predicted most satisfactorily by DFT calculations; the CD spectra were obtained by assuming the prevalence of one “enantiomeric” conformer and the same set of conformers could also be used for MCD, since “enantiomeric” structures present identically in MCD spectra. Full article

(This article belongs to the Special Issue Asymmetric Molecules and Chirality Recognition)

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12 pages, 4051 KiB

Open AccessArticle

Detailed Insight into the Interaction of Bicyclic Somatostatin Analogue with Cu(II) Ions

by Aleksandra Marciniak, Weronika Witak, Giuseppina Sabatino, Anna Maria Papini and Justyna Brasuń

Int. J. Mol. Sci. 2020, 21(22), 8794; https://doi.org/10.3390/ijms21228794 - 20 Nov 2020

Cited by 3 | Viewed by 2062

Abstract

Somatostatin analogues are useful pharmaceuticals in peptide receptor radionuclide therapy. In previous studies, we analyzed a new bicyclic somatostatin analogue (BCS) in connection with Cu(II) ions. Two characteristic sites were present in the peptide chain: the receptor- and the metal-binding site. We have already shown that this ligand can form very stable imidazole complexes with the metal ion. In this work, our aim was to characterize the intramolecular interaction that occurs in the peptide molecule. Therefore, we analyzed the coordination abilities of two cyclic ligands, i.e., P1 only with the metal binding site and P2 with both sites, but without the disulfide bond. Furthermore, we used magnetic circular dichroism (MCD) spectroscopy to better understand the coordination process. We applied this method to analyze spectra of P1, P2, and BCS, which we have described previously. Additionally, we analyzed the MCD spectra of P3 ligand, which has only the receptor binding site in its structure. We have unequivocally shown that the presence of the Phe-Trp-Lys-Thr motif and the disulfide bond significantly increases the metal binding efficiency. Full article

(This article belongs to the Section Biochemistry)

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8 pages, 822 KiB

Open AccessArticle

Investigation of Magnetic Circular Dichroism Spectra of Semiconductor Quantum Rods and Quantum Dot-in-Rods

by Farrukh Safin, Vladimir Maslov, Yulia Gromova, Ivan Korsakov, Ekaterina Kolesova, Aliaksei Dubavik, Sergei Cherevkov and Yurii K. Gun’ko

Nanomaterials 2020, 10(6), 1059; https://doi.org/10.3390/nano10061059 - 30 May 2020

Cited by 4 | Viewed by 3833

Abstract

Anisotropic quantum nanostructures have attracted a lot of attention due to their unique properties and a range of potential applications. Magnetic circular dichroism (MCD) spectra of semiconductor CdSe/ZnS Quantum Rods and CdSe/CdS Dot-in-Rods have been studied. Positions of four electronic transitions were determined by data fitting. MCD spectra were analyzed in the A and B terms, which characterize the splitting and mixing of states. Effective values of A and B terms were determined for each transition. A relatively high value of the B term is noted, which is most likely associated with the anisotropy of quantum rods. Full article

(This article belongs to the Special Issue Electronic and Optical Properties of Nanostructures)

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18 pages, 3867 KiB

Open AccessArticle

Micromagnetic Modeling of All Optical Switching of Ferromagnetic Thin Films: The Role of Inverse Faraday Effect and Magnetic Circular Dichroism

by Victor Raposo, Rodrigo Guedas, Felipe García-Sánchez, M. Auxiliadora Hernández, Marcelino Zazo and Eduardo Martínez

Appl. Sci. 2020, 10(4), 1307; https://doi.org/10.3390/app10041307 - 14 Feb 2020

Cited by 6 | Viewed by 4107

Abstract

There is a lot of experimental evidence of All Optical Switching (AOS) by applying ultrashort laser pulses on ferromagnetic thin films with perpendicular magnetic anisotropy. However, the physical origin behind these processes remains under debate. In addition to the heating caused by the laser pulses, the Inverse Faraday Effect (IFE) and Magnetic Circular Dichroism (MCD) have been proposed as the most probable phenomena responsible for the observations of helicity-dependent AOS. Here, we review the influence of both phenomena by means of realistic micromagnetic simulations based on the Landau–Lifshitz–Bloch equation coupled to the heat transport caused by the laser heating. The analysis allows us to reveal the similarities and differences between both effects. While both mechanisms may lead to the local inversion of the initial magnetic state of a ferromagnetic sample submitted to a train of circularly polarized laser pulses, the Inverse Faraday Effect proves to be more efficient for nucleation and domain wall movement and it reproduces more accurately the different magnetic configurations that the experiments report for different values of the fluence of the laser beam. Full article

(This article belongs to the Special Issue Low-Dimensional Magnetic Systems: Physical Principles and Technological Applications)

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12 pages, 1531 KiB

Open AccessArticle

Investigation of AgInS₂/ZnS Quantum Dots by Magnetic Circular Dichroism Spectroscopy

by Yulia Gromova, Anastasiia Sokolova, Danil Kurshanov, Ivan Korsakov, Victoria Osipova, Sergei Cherevkov, Aliaksei Dubavik, Vladimir Maslov, Tatiana Perova, Yurii Gun’ko, Alexander Baranov and Anatoly Fedorov

Materials 2019, 12(21), 3616; https://doi.org/10.3390/ma12213616 - 4 Nov 2019

Cited by 17 | Viewed by 6026

Abstract

Over recent years, quantum dots (QDs) based on ternary metal dichalcogenides have attracted a lot of attention due to their unique properties and a range of potential applications. Here, we review the latest studies on the optical properties of AgInS₂/ZnS QDs with emphasis on their theoretical modeling, and present our investigations of electronic transitions invisible in unstructured absorption spectra of AgInS₂/ZnS QDs. The analysis of the absorption, photoluminescence excitation (PLE), and magnetic circular dichroism (MCD) spectra of hydrophobic and hydrophilic AgInS₂/ZnS QDs of different sizes enables us to determine positions of electron transitions in these QDs. We demonstrate that the use of the second derivative of PLE spectra provides more unequivocal data on the position of the energy transitions compared with the second derivative of absorption spectra. Analysis of the MCD spectra reveals that the magnetic field induces energy level mixing in AgInS₂/ZnS QDs in contrast to the traditional Cd-based QDs, where MCD is associated only with removing degeneracy of the excited energy level. Full article

(This article belongs to the Special Issue Optical Characterization of Novel Composite and Optically Active Materials)

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11 pages, 3814 KiB

Open AccessArticle

Czochralski Growth, Magnetic Properties and Faraday Characteristics of CeAlO₃ Crystals

by Feiyun Guo, Qiyuan Li, Huaimin Zhang, Xiongsheng Yang, Zhen Tao, Xin Chen and Jianzhong Chen

Crystals 2019, 9(5), 245; https://doi.org/10.3390/cryst9050245 - 11 May 2019

Cited by 16 | Viewed by 4203

Abstract

CeAlO₃ crystals were grown in different growth atmospheres by the Czochralski method. The lattice parameters and space group of CeAlO₃ crystal were determined by Rietveld structure refinement of X-ray diffraction (XRD) data. The influence of Ce⁴⁺ ions in the crystal on the transmittance and crystal color was confirmed by XPS analysis. Magnetization curve at room temperature and temperature dependencies of the magnetic susceptibility in two different directions were measured, indicating that CeAlO₃ crystal has remarkable magnetic anisotropy and there is an abnormal magnetic behavior in the vertical <001> direction in the temperature range of 50–150 K. Faraday characteristics of CeAlO₃ crystal were investigated at room temperature. Verdet constants of CeAlO₃ at 532, 635 and 1064 nm are about 2.1 times as large as those of CeF₃. The reason of large Verdet constants was analyzed based on the Van Vleck–Hebb theory and the magnetic circular dichroism (MCD) spectrum. Full article

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8 pages, 2099 KiB

Open AccessArticle

Influence of Sputtered ZnO and Al:ZnO Top Layers on Magneto-Optic Responses of Yttrium Iron Garnet Films

by Shinichiro Mito, Satsuki Kikuchi, Yasutoshi Ito, Nana Ota and Mitsuteru Inoue

Crystals 2018, 8(10), 396; https://doi.org/10.3390/cryst8100396 - 22 Oct 2018

Viewed by 3590

Abstract

Zinc oxide (ZnO) is a promising material for combining with magneto-optic (MO) materials because it can propagate stable exciton-polaritons, with velocities considerably lower than that of photons in a vacuum. This study investigated the influence of sputtered ZnO and Al:ZnO top layers on MO responses of a bismuth-substituted yttrium iron garnet (Bi:YIG) film. The ZnO top layer modulated the Faraday rotation and magnetic circular dichroism (MCD) of the Bi:YIG around the exciton resonance wavelength of ZnO at 369 nm. Furthermore, Al-substituted ZnO, which is a conductive ZnO, also changed the MO effects around the exciton resonance wavelength. These results imply that the exciton-polaritons in ZnO affect the MO interaction, because of their considerably low group velocity. The results suggest potential for controlling the MO response via excitons. Full article

(This article belongs to the Special Issue Spin-dependent Optical, Plasmonic, Confinement and High-frequency Phenomena and Applications—Mini-symposium, ETOPIM11)

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